>> reporter: toss in sarah palin's endorsement and she's got a solid chance of taking the republican nomination. >> if she were by some miracle to be our nominee, that we would lose this seat and lose it by unprecedented numbers. >> reporter: mike castle is a republican who often works with democrats. he's for abortion rights, for gun control, and with a democrat has co-sponsored a bill to allow stem cell research, all fueling the tea party tempest. >> the republican party has lost its way. they get behind candidates like my opponent, who don't even support the republican platform. who continue to support the democrats' agenda lock, step, and barrel. >> reporter: castle is hammering back hard, attacking o'donnell on problems with her personal finances. the gop establishment is watching tuesday's primary vote very closely. tea party favorites have already beat the establishment choice in at least six states. rob and vinita? the alleged underwear bomber who tried to blow up a delta jet over detroit on christmas says