Rep. Eric Cantor (R-VA), Chief Deputy Majority Whip, is the first elected official I can think of to (kind of) endorse an Israeli strike on Iran's nuclear facilities. Here's an extract from a letter he wrote to Secretary of State Condoleeza Rice:
A nuclear-capable Iran would be a major step back for security in the Middle East. As you know, Iranian President Mahmoud Ahmadinejad, recently advocated for the complete annihilation of Israel. His radical statements are reprehensible and cause for great concern. I share the belief that, we have a duty to protect our interests and allies in the region from nuclear attack or nuclear terrorism.
Furthermore, I believe the failure of the IAEA to disarm Iran has created a situation in which Israel might be justifiably forced to act in its own self-defense by preemptively attacking Iran.
The whole thing (PDF document) here.