They may go ahead because they feel that Barry would have no choice but to support them before an a election. If he wins he will make it harder on them. Hell he may have offered them a deal to start it so it helps him out. Bunch of new jets next year for a October 12th start date this year.
I don't think Israel trusts Obama enough for that to be a consideration. I think they will strike only when they believe that waiting any longer will bring about their end. The consequences of a strike like that would be pretty bad with US support. It would be much worse without it.