"a" grade, john berman. the race for the republican presidential nomination is growing tighter by the day. take a look the this. just released national quinnipiac poll, donald trump and dr. ben carson locked in a dead heat as the top choice of republican voters. let's get straight to athena jones with more on these numbers. >> good morning, michaela. this poll is different from two other national polls out in recent days that had carson opening up a lead. but it's still more evidence that the race is shifting. trump and carson are neck and neck. they're within the poll's margin error. when you compare the numbers to september, trouble's numbers are pretty much unchanged but that carson and ted cruz have each gained six points and marco rubio has jumped five points to third place. meanwhile, jeb bush, you can see there is way down at 4%. he's lost six points in that time. there's more bad news in this poll for bush. he has the worst net unfavorability numbers of any