McCain is on his way to be the GOP nominee. Romney droped out and Huckabee doesn't have a chance.
Obama won all the primaries over the weekend (5) which puts him barely above Hillary. Polls show Obama may win more tonight. More elections coming up which could still put Hillary in the lead, especially with a big state like Texas with a large latino base going for Hillary.
It's also the first time Obama is in the lead in national polls.
Looks like Obama will get the nod but there are other factors including the votes of "superdelegates" (votes of party officials) if the amount of delegates is about even.