dan wheldon, leaving racing fans in shock and grief. i m wolf blitzer in las vegas, you re in the situation room. we are now in las vegas with the republican hopefuls will face off tomorrow night in the western presidential debate. it comes at a pivotal point in the contest with herman cain now near or at the top of the various polls. but he sparked an uproar over the weekend about a controversial remark about immigration. a very sensitive issue here if nevada. cnn s jim acosta is with us. this is a big one here and in a lot of other states as well herman cain said he made these comments before when he hosted his radio show in atlanta. he is finding out that those remarks can bring in viewers and listeners but may not work as well on a presidential campaign. herm yan cane insists these comments did not cross the line. it ll be 20 feet high. barb wire on the top. it will be electrified. and there is going to be a sign on the other side that said, it will kill you. warnin