True, but assuming that O will be on the ballot in 2012 with a "D" aside his name, dislike for Obama will translate into dislike for the 'Rats, at least in the presidential race.
For the general population, Obama at the top of the ticket will discourage votes for ANY Democrat, but, as you point out, Jewish voters are used to parsing their ballots, opting for a liberal Republican over an anti-Semite Democrat.
So Jews in Florida might vote for a Republican for president but will dutifully vote Bill Nelson over the Republican senate candidate.
I’ll believe in a changing Jewish vote when it shows up in Florida and hopefully New Jersey, the only states where the Jewish vote really matters.