Zogby has some crediblity because Rush liked his guesses and he guessed right more than wrong. But I think he has results designed to get publicity rather than be right. I don't think there is one chance in 50 that Jeb Bush has a 15 point lead in Florida. Zogby publishes a few outrageous poll results so it gets him publicity. He will be right on some... but don't put a lot of faith in his outrageous polls. I think he had McCain in South Carolina in the 2000 primary for a while. That was pure garbage.
Look at where the candidates were today and yesterday. I don't know what is happening in Texas but McBride had people working in Black Churhes and He has campaigned in southern Florida in the final days. If McBride doesn't have 90 percent of that vote already he is a gonner.
Bush was in south Florida too. If bush had problems with his base he would be in Northern Florida. Both are campaigning for McBrides base.
Look at what the texas candidates are doing. Look at the media stories. They will contain hints that tell you. When a story says what x must have happen to win, it means x is losing. >
I don't remember seeing leads changing as the center picks candidates. Once some of the center starts to go more for one candidate than the other, there is not normally much change except the undecided number goes down. It takes a defining event to change that ratio. I don't think there has been a defining event to change the Texas vote.