is just over two weeks away. here's nancy cordes. >> hillary clinton has been there. >> reporter: nearly 20 members of the congressional black caucus vowed today to campaign for clinton. hakeem jeffries of new york was one of them. >> hillary clinton has been there from the very beginning to deal with the gun violence epidemic and its impact on african american communities across the country. >> reporter: she has prayed with black pastors, met with black lives matter protestors and is airing this new ad in the south. >> you have to face up to the hard truth of injustice and systematic racism. >> reporter: her campaign says sanders is a johnny-come-lately on race issues. he says he got his start in activism during the civil rights movement. georgia congressman john lewis scoffed at that today. >> but i never saw him. i never met him. i chaired the student non-violent coordinating committee, but i met hillary clinton. i met president clinton. speak frequently about incarceration rates and poverty. >> 51% of young african american kids in this country are unemployed or underemployed. that is a national tragedy. that has got to change. >> reporter: the influential writer tanehisi coates called sanders the best option, and performer harry belafonte endorsed him today. >> i think he represents opportunity. i think he represents a moral imperative. >> reporter: when clinton and sanders face off here in milwaukee tonight, she'll argue that she will actually do more to carry on the legacy of the nation's first black president, while he'll argue, scott, that he'll actually do more to help minorities with his proposals for things like free public college tuition. >> pelley: nancy, thanks very much. the republican primary in south carolina is just nine days away, and the attacks are getting louder and cruder. >> we win here, we're going to run the table. >> reporter: donald trump in south carolina by turns optimistic and vulgar. >> what the hell is this guy talking about? i don't know what the hell i was doing. what the hell are we thinking? >> senator marco rubio. >> reporter: marco rubio campaigning in a state with more conservative culture instincts criticized trump's language as an assault on decency. >> you turn on the tv, you have the leading presidential candidate saying profanity from a stage. profanity from a stage. i mean, all these things undermine what we teach our children. >> reporter: jeb bush also piled on. >> he says, "we're going to bomb the blank, blank, blank out of isis," using a vulgarity. that's not leadership. >> reporter: in 2012, about two-thirds of republican primary voters in south carolina described themselves as evangelical or born-again christians. that represents a challenge for trump despite his large lead in the polls. divided. >> when he claims he's a christian and he can only quote one verse from the bible, i mean, come on. >> i think that's what a lot of people like about him. he says what he means and means what he says. i love it. >> reporter: trump today pulled an ad criticizing ted cruz and said he would only run positive ads from now on. scott, john kasich's campaign has been doing that for weeks and described bush's efforts in south carolina of having all the joy of a texas chainsaw massacre. >> pelley: thanks, major. cbs news will host the next republican debate. that's saturday evening at 9:00 eastern time. and john dickerson is the moderator. in another important story tonight, the zika virus, suspected of causing birth defect, keeps spreading. 79 cases now in the u.s. territories in the americas. brazil is the hardest hit. with the olympics there this summer, hard choices have to be made. here's dr. jon lapook. >> morgan in the box. >> reporter: the u.s. women's soccer team started on the road to rio last night with a win in game. the team's goalkeeper, hope solo, is raising concern about the risk of zika infections during the game. >> the olympics, if they were today, i wouldn't go. today. so we have six months. we have a little bit of time to figure things out. >> reporter: u.s. olympic committee c.e.o. scott blackmun tried to address questions and doubts in a memo to perspective olympians. he said the organization is working with the c.d.c. and infectious disease specialists to closely monitor the situation, but no matter the preparation, he wrote, there will always be risk associated with international competition. an official with the rio games told cbs news all rooms in the conditioned, and venues will be inspected daily to remove standing water where mosquitoes might breed. the population of the mosquito that carries zika goes down significantly in the cooler, dryer months of august and september, when the games will take place. the main worry is the suspected link between the virus and microcephaly, an unusually small head at birth. that link has been strengthened within the past day by reports both in brazil and the united states. the virus has now been found in the placenta of mothers who miscarried and the brain tissue of newborns with microcephaly who died. i spoke with an official from the rio olympic organizing committee today and asked, are there any thoughts of canceling or postponing the olympics or it is full steam ahead, and he said, full steam ahead. in fact, this weekend they're having a test event in rio for the driving competition. >> pelley: jon, thanks very much. in oregon today, a six-week armed anti-government protesters ended peacefully. the final four hold-outs surrendered. one refused to go quietly, though, ranting, "liberty or death." tonight we've learned that the isis terrorist group in syria and iraq has chemical weapons in its arsenal. in a rare interview for "60 minutes," we spoke to the director of the c.i.a., john brennan. >> we have a number of instances where isil has used chemical munitions on the battlefield. >> pelley: artillery shells? >> sure. >> pelley: isis has access to chemical artillery shells? >> uh-huh. there are reports that isis has access to chemical precursors and munitions that they can use. >> pelley: the c.i.a. believes that isis has the ability to manufacture small quantities of chlorine and mustard gas. and the capability of exporting >> i think there's always the potential for that. this is why it's so important to cut off the various transportation routes and smuggling routes that they have used. >> pelley: are there american assets on the ground hunting this down? >> u.s. intelligence is actively involved in being part of the effort to destroy isil and to get as much insight into what they have on the ground inside of syria and iraq. >> pelley: we'll have our full interview with c.i.a. director brennan, including the threat that he says keeps him up at night. that's this sunday on "60 minutes." millions have fled syria, but there are tens of thousands who can't get out. they're trapped between russian bombers and a closed turkish border. holly williams is following this. >> reporter: imagine the terror, never knowing where and when the warplanes will hit next. these videos, but they appear to show the aftermath of air strikes on the town of tel rifaat this week. in the syrian regime's new offensive, which is backed by russian air power, civilians are once again paying with their blood. crossing the border into turkey, we met abdul karim bahloul, who runs a school in tel rifaat. "the shelling and air strikes are random," he told us. "homes are destroyed and children's bodies lie in shreds on the ground." he told us he came to ask the turkish authorities to give refuge to children from the town, but after absorbing more than two million syrian, turny's reluck tantd to let any more in. syrian regime forces have now nearly encircled the city of aleppo. the u.n. fears that 300,000 they were in the town of madaya during a siege by the regime. more than 40 starved to death. dalia al-awqati told us that her charity, mercy corp, feed and clothe 500,000 people in northern syria every month. >> it's not much, but it's essential to keep a family alive. >> reporter: now they're racing to get food parcels to families in aleppo city, fearing more starvation in a country that's already exhausted by a senseless war. and as if syria's war wasn't complicated enough, today some american-backed rebels told us they were attacked by kurdish fighters who were also supported by the u.s. now, the kurdish fighters say it wasn't deliberate, but, scott, this shows just how difficult it is for the u.s. to unite different factions on the ground in syria. thanks. so what can the u.s. do to stop for that we turn to margaret brennan. margaret? >> reporter: well, today the u.s. is trying to broker an immediate ceasefire. today secretary kerry pushed both russia and iran to stop attacking syrian civilians in aleppo and allow in aid to besieged areas, but the russians that. in fact, vladimir putin's military has cut off supply lines to the u.s.-backed rebels, and u.s. officials warn that that strengthens both isis and assad and it leaves the u.s. with little leverage in a war president obama has resisted getting involved in for five years now. >> pelley: margaret brennan at the white houseful margaret, thank you. today cleveland mayor frank jackson apologized to the family of tamir rice after the city billed his estate $500 for ambulance services. the city also tore up the bill. in 2014 a cleveland cop shot he was holding a gun that turned out to be a toy. he died the next day at the hospitals. the officer was not charged. in a big development today, scientists have announced what may be among the greatest discoveries in the history of physics. they believe they found gravity waves, predicted by einstein but never observed, two huge antennas, one in washington state, the other in louisiana, detected a gravity wave last september. this confirms einstein was right when he described the universe as "like a fabric, woven from the three dimensions plus time." what physicists call space time. the gravity wave was set off by two black holes that collided, sending a ripple through the fabric. the effect is so tiny one scientist estimated the ripple compressed the entire milky way thumb. observing fa the fabric of the universe stretches and compresses may open an entirely new understanding of nature. coming up next... how explosions like this are improving airport security. and a scoop by a newspaper sets off an uproar when the "cbs evening news" continues.hm kept coming back on my long-term control medicine, i talked to my doctor and found a missing piece in my asthma treatment. once-daily breo prevents asthma symptoms. breo is for adults with asthma not well controlled on a long-term asthma control medicine, like an inhaled corticosteroid. breo won't replace a rescue inhaler for sudden breathing problems. breo opens up airways to help improve breathing for a full 24 hours. breo contains a type of medicine that increases the risk of death from asthma problems and may increase the risk of hospitalization in children and adolescents. asthma is well controlled on a long-term asthma control medicine, like an inhaled corticosteroid. once your asthma is well controlled, your doctor will decide if you can stop breo and prescribe a different asthma control medicine, like an inhaled corticosteroid. do not take breo more than prescribed. see your doctor if your asthma does not improve or gets worse. ask your doctor if 24-hour breo could be a missing piece for you. see if you're eligible for 12 months free at mybreo.com. it was always just a hobby. something you did for fun. until the day it became something much more. and that is why you invest. the best returns aren't just measured in dollars. toenail fungus!? whaaat?!? fight it! with jublia. jublia is a prescription medicine... ...used to treat toenail fungus. use jublia as instructed by your doctor. jublia is workin' it! most common side effects include... ...ingrown toenail,application site redness,... ...itching, swelling, burning... ...or stinging, blisters, and pain. oh!! fight it! with jublia! now that's a red carpet moment! ask your doctor if jublia is right for you. visit our website for savings on larger size. >> pelley: the tsa is looking for a more professional and effective force of airport screeners. kris van cleave is in glenco, georgia, tonight at the tsa's new training academy. [explosion] >> reporter: seeing the power of even a small explosive made the threat real for nearly 200 soon-to-be airport screeners. >> reporter: they're going through a new program designed to address troubling security gaps when the transportation security association. a damning report last summer found screeners failed to detect 67 of 70 suspicious items brought through airport checkpoints. peter neffenger became the tsa administrator in july. >> what the inspector general's results have told us is you can never take you eye off the mission. >> reporter: shawn weeks-freeman is one of the academy instructors. on august 11, 1982, she was a flight attendant on pan am flight 830, standing just rows from where a terrorist bomb exploded while the 747 prepared to land in honolulu. one person was killed, more than a dozen injured. >> when i talk to my class, i tell them, you're not here by accident. and i wasn't saved at that moment by accident. because that threat in 1982 is today's threat still. >> reporter: the academy marks first time all transportation standardized training. previously new hires were largely trained on the job at their home airport. if they're getting through checkpoints today with one of their teams trying to bring things that should be flagged, will those things be caught? >> i think we'll catch them today. >> all of them? >> i don't know if we'll catch everything. i sure hope we catch all of them. >> reporter: the students will work at this mock checkpoint. it's complete with all the equipment, scott, they're going to use in the field. >> pelley: kris. thanks. if you have moderate to severe rheumatoid arthritis like me, and you're talking to your rheumatologist about a biologic... this is humira. this is humira helping to relieve my pain and protect my joints from further damage. this is humira giving me new perspective. doctors have been prescribing humira for ten years. humira works for many adults. it targets and helps to block a specific source of inflammation that contributes to ra symptoms. humira can lower your ability to fight infections, including tuberculosis. serious, sometimes fatal infections and cancers, including lymphoma, have happened, as have blood, liver and nervous system problems, serious allergic reactions, and new or worsening heart failure. before treatment get tested for tb. tell your doctor if you've been to areas where certain fungal infections are common, and if you've had tb, hepatitis b, are prone to infections, or have flu-like symptoms or sores. don't start humira if you have an infection. talk to your doctor and visit humira.com. this is humira at work. hey you look good. thank you, i feel good. it all starts with eating right. that's why i eat amaz!n prunes now. they're delicious and help keep my body in balance. i love these. sunsweet amaz!n prunes, the feel good fruit. 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>> weeding out students because we think they might not do well look better, that's not mount st. mary's. >> reporter: eagan was the faculty adviser to the school paper and says he's being punished for accurate but embarrassing reporting by the students. you did not tell them what to write? >> i did not, not in any way. anybody on campus that knows the students knows that nobody would manipulate these students. >> reporter: they can't be manipulated. >> they are independent, strong, bright people. >> reporter: a petition protesting the firing of eagan and another professor has been signed by about 7500 professors across the country, and, scott, the university declined our repeated requests for an interview. instead they issued a statement saying the two professors had violated the code of conduct. >> pelley: chip reid, thanks, chip. in a moment how a mother's words joy. it's just a cough. if you could see your cough, you'd see just how far it can spread. robitussin dm max soothes your throat and delivers fast, powerful cough relief. abdominal pain. urgent diarrhea. it could be ibs-d new prescription xifaxan is an ibs-d treatment that helps relieve your diarrhea and abdominal pain symptoms. do not use xifaxan if you have a history of sensitivity to rifaximin, rifamycin antibiotic agents, or any components of xifaxan. tell your doctor right away if your diarrhea worsens while taking xifaxan, as this may be a sign of a serious or even fatal condition. tell your doctor if you have liver disease or are taking other medications, because these may increase the amount of xifaxan in your body. tell your doctor if you are pregnant, plan on becoming pregnant, or are nursing. the most common side effects are nausea and an increase in liver enzymes. if you think you have ibs with diarrhea, ask to your doctor about new xifaxan. you can't predict the market. but through good times and bad... ...at t. rowe price... ...we've helped our investors stay confident for over 75 years. t. rowe price. invest with confidence. if you're looking to save money on your medicare part d prescriptions, walgreens says, carpe med diem. seize the day to get more out of life and medicare part d. just switch to walgreens for savings that'll be the highlight of your day. now preview the cost of your copay before you fill. you can even get one-dollar copays on select plans. big changes underway in des moines's east village. at six, what projects are underway and what it will mean for the >> pelley: our final story tonight is written on the face of a young child whose joy mere words cannot describe. here's elaine quijano. >> elsa had magical powers and could create things out of snow and ice. >> reporter: four-year-old mattie zapata can't get enough of her books on tape. >> anna was delighted. >> reporter: because the voice is her mother, mandi balderas, locked in a prison four hours away. >> i told her how i missed her. even though i'm not there physically, i know she's sitting there listening to my voice, spending that time with me. >> reporter: each month balderas and other selected inmates choose a story to record, then mail it home. it's called storybook project, and it runs in six women's prisons across texas. >> it was a sunday afternoon at the end of may. >> this story begins within the walls of... we were together. >> reporter: 64% of incarcerated women nationwide lived with their children before prison. storybook tries to ease the pain of separation. mattie was 18 months old when her mother went to prison for a d.w.i. crash that killed the other driver, a crime of manslaughter that victimized her daughter, too. >> i was crying for mmy. -- mommy. >> reporter: how come? >> because i miss her. >> reporter: if it wasn't for the book, she wouldn't be able to have the bond we have now. i know that means something to her, and i know it means something to me. >> reporter: but the fact is you got behind the wheel of the car when you had alcohol in your system, and a person is dead because of that. didn't you forfeit your right to do things like this when you made that decision? >> yes, i made a decision, but it's about how we handle the circumstances. and that's how i'm choosing to handle the circumstances, by helping the kids the best way i can from where i'm at. >> hey, mattie, it's me, mommy. >> reporter: balderas has four years left of an eight-year sentence. when she finally reunited states with -- reunites with her family, she hopes her children won't mistake her voice for a stranger. >> you are my sunshine, my only sunshine. >> reporter: elaine quijano, cbs news, columbus, texas. >> i love you always. mommy. >> pelley: and that's the "cbs evening news" for tonight. for all of us at cbs news all around the world, [kcci captioning is brought to you by the iowa clinic.] announcer: you're watching kcci 8 news. >> the final hearing to your the fate of the pipeline arrived -- wrapped up a short time ago. why it could be a while before steve: brace yourself -- the eastside of downtown des moines will soon be home to even more construction. we have the traffic changes it's about to cause. stacey: and ames is home to number one. and we're not talking the cyclones. why ames is ahead when it comes to jobs. good evening, thank you for joining us. another round of snow moves through central iowa tonight. let's take a live look from our downtown skycam. we can see that snow is already starting to fall. houck -- how much can we expect? kurtis: light, fluffy snow falling. it will slick of the roads west and south of the metro. you can see the band to the northwest -- the bands to the northwest. this is moving generally off to the south. the snow has lightened up a bit, but snow picks up from dallas county back and through northern ottoman county. all of that will sweep through as the system drops to the south in jefferson, already snow on the ground. totals live this scum lesser amounts north and northeast, it looks around an inch in the metro. i think it will be a bit more on the line from oc a list to ottoman in carroll county. folks there might get an inch to two inches of snow. blowing snow is not an issue tonight. when pick up tomorrow -- wind picks up tomorrow. gusty winds with sunshine could create blowing snow. single digits with a high around 21. steve: it is a final day for the iowa utilities board liberations, and no decision on the highly controversial bakken pipeline. the board is weighing whether to allow dakota access to build a crude oil pipeline across 18 kcci's rose heaphy was at today's board meeting. she shows us where the board's discussion now stands.