The House Judiciary Committee later this week. Will staff lawyers get to question barr or will he boycott the hearing . Isis leader returns. The terrorists release a new video apparently showing Abu Bakr Al Baghdadi for the first time in five years, praising the suicide bombings in sri lanka that killed hundreds of people and calling for more attacks. Im wolf blitzer. Youre in tthe situation room. Were following breaking news. A major terror plot thwarted in california where police have arrested a suspect they say was, quote, consumed with hate and bent on mass murder. Also breaking, democratic president ial candidate joe biden, proclaiming himself a union man as he courts working class voters in his First Campaign rally, this one in pittsburgh. President trump, meanwhile, as tweeted about biden at least four times today, ignoring advisers who warn giving a rival too much attention could backfire. Well talk about that and more with congressman steve cohn of the Judiciary Committee and our correspondents and analysts are also standing by. First, lets get to the breaking news out of los angeles, where Officials Say they have thwarted a major terror plot. Our Justice Department, Jessica Schneider is working the story for us. Jessica, were now learning some very disturbing new details. We are, wolf. This is a 26yearold former army soldier. He served in afghanistan for four months back in 2012, but hes allegedly been plotting an attack out in california for weeks. Authorities say Mark Steven Domingo purchased long nails to pack into ieds and even staked out a spot on long beach, california, where a rally was being held this weekend. But authorities got to him just in time. The fbi had been tracking him by way of a confidential human source and when that source delivered the bomb materials just a few days ago, thats when members of the joint Terrorism Task force moved in and arrested him. The fbi first found out that domingo may have had these thoughts when he posted an online video professing his muslim faith and then post eed online this. He said, America Needs another vegas event. That refers to the mass shooting in las vegas back in 2017. And in the weeks after that, domingo tweet eed again, he tweeted, after that mosque attack in new zealand just last month, that, quote, there must be retribution. Authorities say that domingo is under arrest. He will be formally charged with providing and attempting to provide Material Support to terrorists. But wolf, they got to him, they had been tracking him. There was this confidential human source and they arrested him just a few days ago, right after he had scoped out the location where Authorities Say he wants to plot this attack and detonate this bomb. He was obviously also proficient with weapons, too, given his military background. And thats part of what authorities said in their press conference just a little while ago. But again, they were tracking him. They saw him posting these messages about las vegas and about the mosque attack in new zealand in these online forums and then they began tracking him. Thats when they worked with him with a confidential human source. So, right, while he was a danger, they said they had eyes on him the whole time. They stopped it. Well continue to follow this story for our viewers. Jessica schneider, thank you very much for that report. Well have more details coming up later this hour. And next, theres other developments unfolding right now. You just saw it live on cnn. The Joe Biden Campaign rally. Jessica dean is in pittsburgh live on the scene. So walk us through the former Vice President s bottom line message. Reporter good evening to you, wolf. The bottom line message is that hes saying he wants to reward work, not just wealth here in the United States of america. He made the argument today, that this economy is not working for everyone. That its only working for a Certain Group of people in the United States and that he has a plan to build that up, to make more people feel included in that. Some of the ideas that he talked about today welcome closing tax loopholes, a 15 minimum wage, reversing the trump tax cuts. Also, a medicare public option. Some of the things he talked about in this union hall, saying, im a union guy. Take a listen to what he had to say. I also came here because, quite frankly, folks, if im going to be able to beat donald trump in 2020, its going to happen here in western pennsylvania. With your help. Say this simply and clearly, and i mean this, the country wasnt built by wall street bankers and ceos and hedge fund managers. It was built by you, it was built by the Great American middle class. A and we heard the middle class over and over again. You heard him talking about it himself. He says, if hes going to beat President Trump, hes going to do it here in pennsylvania. You can bet that hell be here over and over again, working to get his message across. Also today, for former Vice President joe biden, he received an endorsement from the firefighters union. T t this was a big one for joe biden. But it also ignited some twitter back and forth between the president who tweeted, wolf, as you mentioned, four times at former Vice President biden today. He said, the firefighter leadership will always support democrats, although the membership wants me. Biden also tweeting back at ft. Saying, im sick of this president bad mouthing unions. We need a president who honors them and their work. And he talked over and over again about the importance of unions. How if he is president , that he will do everything he can to support them and build them up. It was a message we heard throughout the day. Next up for the former Vice President , he will be headed to iowa. Wolf, its his first swing through the caucus state since he made his announcement last week. It was very important to him to get to those early states as soon as he possibly could. So onward to iowa tomorrow. His First Campaign rally since announcing his run for the democrat president ial nominee. Lets get to more on the president s twitter attacks on the former Vice President. Our white house correspondent, Kaitlan Collins is standing by. Kaitlan, theres some concern apparently over there, all afternoon, all this attention that biden is receiving from the president could wipnd up actualy hurt the president. Tell us about that concern youre hearing about. Theyre worried it could evaluate joe biden. In recent weeks, the president has been questioning people about whether or not they think joe biden could beat him. And his uneasiness over joe biden entering the public race burst into public view today on the president s twitter feed. But as the president is looking ahead to 2020, hes being forced to look back at comments he made in 2017. Reporter tonight, a president usually known for his confidence appears to be unnerved by his latest rival, former Vice President joe biden. Aides insist President Trump isnt worried about running against biden, but hes clearly on his mind. Hell happened to biden. Ive never saw that before. It just doesnt look like the same biden. I said, is that really the same biden . He doesnt look the same to me. Reporter trump referenced the former Vice President on twitter at least four times today alone. And while some advisers are urging the president not to single out any democratic president ial hopefuls just yet, those closest to the president are following his lead on biden. Why is he using charlottesville to launch a candidacy, as somebody who was in the senate for decades, was Vice President for eight years. Reporter the white house has been on defense after biden made trumps comments about a 2017 White Nationalist rally in charlottesville that left a counterprotester dead a central focus of his campaign announcement. When President Trump condemned racism, bigotry, evil, violence and took it many steps further and called out neona neonazis, White Supremacists, kkk, that is darned near perfection. Reporter after a shooting outside of a synagogue in california left one person dead and others injured, President Trump offered a fullthreated denouncement of hate. The latest shooting six months after a shooting at a synagogue in pittsburgh killed 11 has put the rise of White Nationalism at the forefront of the 2020 race. The fbi says hate crimes are on the rise for the third year in a row. But six weeks ago, after a gunman killed 49 muslims at two mosques in new zealand, trump downplayed the threat. I dont really. I think its a small group of people that have very, very serious problem. Reporter his allies say his critics are misrepresenting his remarks about what happened in charlottesville. If you go back and look at what trump said, trump said clearly that he was opposed to White Supremacists, he was opposed to klansmen, he was opposed to nazis. He says it clearly. Reporter but after the protest two years ago, the president blamed both sides. We condemn in the s hatredig violence on many sides. Reporter and then two full days later, after facing widespread criticism from republican lawmakers and ceos, the president named names. Those who caused violence and its name are criminals and thugs, including the kkk, neonazi, White Supremacists and other hate croups that are repugnant to everything we hold dear as american. Reporter the next day, after fuming from coverage that said he hadnt gone far enough, trump defended his first tam. I think theres blame boent sides. You look at both side, i think theres blame on both sides. Reporter now, wolf, during an event here at the white house this afternoon, the president did not answer a question about whether he still doesnt think that White Nationalism is on the rise. But back to the advice hes getting from advisers about not evaluating any of these candidates just yet, other aides who know the president well say they fear as he sees more democrats getting air time and sucking up some of the political oxygen, hes going to do whatever he needs to stay in the news. Lets bring in our experts for some analysis. David chalian, he spoke for about a half an hour. Whatd you think . You can see why President Trump has joe biden under his skin, why hes getting under his skin a libtd, precisely because of how joe biden was messaging and where he was. He was in pittsburgh, taking a union endorsement, showing the example, i am the person who can make an economic appeal on middle class values to these people that drifted away from this party last time and went to donald trump. That is why trumps advisers are so fearful of him. It was so sort of shocking to my ear to hear joe biden. It was as if Sherrod Brown did get into this race. Dignity of work, real economic populism. He sounded a little Bernie Sanders at times, wolf, taking on millionaires and billionaires. He continued to call himself middle class joe and wear that as a banner of proud. This is the economic piece of the overall biden rationale for his presidency, which is to campaign on rebuilding the middle class and win back those voters that drifted away. On that point, let me play a little clip. This is joe biden moments ago in pittsburg pittsburgh. The stock market is roaring, but you dont feel it. There was a 2 trillion tax cut last year. Did you feel it . Did you get anything from it . Of courim still broke of course not. Of course not. All of it went to folks at the top. Thats what people are talking about as it relates to sanders. All of it went to folks at the top. I was most struck by the fact that joe biden is running for a version of the Democratic Party that if you were online on a daily basis, you wouldnt think exists, which is in the midwest, in the industrial midwest, lower to lower middle class voters, its a very different kind of campaign in look, where he starts it matters. He starts in pittsburgh in a union hall. Nobody else has done that and i think theres a you know, the Bernie Sanders idea of what the Democratic Party looks like and who it will elect, the Kamala Harris idea, even the Pete Buttigieg image of who it will elect is very different than biden. And i think that thats that that will be a very clear line. Joe biden is not running to answer a poll. Its an interesting cam condemning antisemitism. The synagogue within the past six months. White nationalism, going after White Nationalism. Its so far in the last few days, theres been a major thrust of his, in an attack format against the president. And the tragic events this weekend in poway sort of underscored this. But before this happened, before the shooting at the synagogue happened, he already went to charlottesville, very deliberately, and delivered this rebuke to President Trump for his failure to be a moral leader after the charlottesville death of Heather Heyer and all of the disruption there two years ago. In Vice President bidens video where he announced his candidacy, he said, this campaign is about, everything that makes america america. And that is a direct response in my view to trumps tag line of make America Great again. These are two big visions of america going at each other, rather than a lot of the other Democratic Candidates who are looking at very specific narrow policy ideas, green new deal, jobs, et cetera. Because he keeps talking about the soul of the nation is at stake right now. Thats a theme that he keeps referring to, at least over the past few days, are a the election campaign. Theyre worried about, precisely, potentially ily wisconsin, which the president carries. Thats exactly right. And ive said this before, i think the president s twitter feed is a great window into his n neurosis. I think in a way that trump avoids this, because of the steps and the measures hes taken with regard to nafta and thus far, is biden is going to face some scrutiny for his record here. Obviously, you dont need me to tell you hes selfstylings himself, to foster a connection with these labor unions and middle class, the middle class workers. But at the same time, theyre going to look back on his record, he supported nafta, he supported tpp. Bernie sanders right before his announcement speech released a little bit of a subannouncement aimed at biden saying that he would call for an eo to end federal contracts with people outsourcing jobs to American Workers and also that he would label china a currency manipulator. We have not seen any of those kinds of policies from biden yet. He said that he used his line twice, lets reward wealth. Its still very much tbd, whether or not he can actually match the policies to support labor unions in the way that hes describing himself. And jackies right, too. I think its worth note iing th. Has real appeal to independent or a republican voter, potentially, in pennsylvania. I think the issue is theres 19 other people that joe biden has to beat in a primary in a Democratic Party, that he is gambling hasnt changed as much as some of the other people believe it has. That biden speech, bill clinton could have given a similar speech to that. Theres no that much different there. Hes saying that the party that the Democratic Party of unions, of middle class working men and women, thats who this party still is. Its not necessarily the urban, highly affluent, you know, highly educated. I mean, its a gamble that might pay off. This is just day one, right . Totally, totally but he does choose what he says in the beginning on purpose. This is the economic rationale. You are right, hes making that play. But for us to think hes going to go through the next eight months and hes not going to have to participate in all of these issues he will. Like we saw Hillary Clinton flip on tpp. He will have to go through this, how he maintains this authentic self of him, this version of him through his process is going to be i think thats right. And i do think, like everybody is saying, he is clearly grabbing looking for the working class voter in the american heartland. I dont think Vice President biden, being from the former administration, should give up on the other economic story that he could tell, which is that the stock market of the Obama Administration did better than trumps, that unemployment came down over three points under president obama and Vice President biden. So if he goes away from that. I think hell hurt himself in the general election. This Washington Post, this abc news poll shows that just came ou