"Republicans in the Senate are telling AIPAC "don't you dare."

"...AIPAC,.. is afraid of defying right-wing Republicans in the Senate. Sen. Jon Kyl (R-AZ), in particular, is telling AIPAC "don't you dare." His reason is simple: Minority Leader Mitch McConnell (R-KY) has ordered Republicans to block anything the President submits to the Senate except, of course, tax cuts for millionaires. That includes START.  (The good news is that Kyl may come around and then AIPAC can too.)
The case that START is critical to Israel is impossible to dispute. In a letter to AIPAC, Senators Carl Levin (D-MI) and Chuck Schumer (D-NY) explain that there is one gigantic factor that should matter more to the so-called pro-Israel lobby than pleasing Republicans: Iran. Rejecting the treaty will probably cause Russia to abandon the US-led effort to prevent Iran from getting nuclear weapons. ..."