A Gallup poll pegs Jewish support for President Obama at 60% -- 14 points higher than the general population, which is the typical margin. This figure was statistically unaffected (note the wide margin of error, however, due to the small sample size) by President Obama's May 19 Middle East policy speech which called for '67 based-borders in a two-state solution to the Israeli/Palestinian conflict.
Arm-chair analysis of Jewish voters tends to make some rather elementary mistakes about how Jews will think in the voting booth. Basically, the stock assumption behind GOP efforts to break into the Jewish voting bloc is that they are single-issue Israel voters. Which, by and large, isn't true -- polls consistently demonstrate that while Israel matters to many Jewish voters, it is subordinated to other issues -- the big ones all voters care about, like the economy and education.
Of course, there are Jewish voters for whom Israel is a more prominent voting issue. But for these voters, that greater attachment also comes with a more involved opinion on the matter. They don't just "support Israel", they have particular policy options or politicians they think are good or bad. So some might identify as Likudniks, but others might identify more with Kadima, or Labor, or Meretz. Whether or not that enhanced involvement translates to Republicans is not going to be dependent on how high Republicans dial up the volume on the "WE ARE PRO-ISRAEL" megaphone -- it will depend on the affinity between the Republican's specific policy agenda with respect to Israel, and that held by each individual Jewish voter. If one of these voters thinks that a two-state solution is critical and the United States needs to throw its weight around to make it happen sooner rather than later, obviously that won't help the GOP one bit.
With regards to Netanyahu in particular, Bibi has never been particularly popular amongst American Jews -- a lot Jewish voters who know a lot about Israel believe he's a nutjob, and this dates back to his first tenure as Prime Minister well before his spats with President Obama. There's no reason to suspect, in other words, that amongst high-information, high-passion Jewish voters, a battle between Obama and Netanyahu is one that Netanyahu would win.