a) Obama's support among Jewish voters in South Florida is going to be weak. I would expect lower than usual turnout for this demographic.
b) Unlike most other swing states, the Republicans hold close with the Democrats in Party ID. In 2008, the breakdown was Democrat (37%) Republican (34%) Independent (29%)*. The enthusiasm is on the GOP's side, the make-up of partisans is going to reflect that. Assuming that Romney is winning Independents handily, by 5-10%, I don't see Obama pulling it out.
Or simply put: The President won Florida by 2 points in 2008 winning independents by 7 points and with 12% of the GOP vote. This is NOT happening.
* source: cnn exit poll 2008: http://www.cnn.com/ELECTION/2008/results/polls/#FLP00p1