President Barack Obama will personally woo senators on Iran Tuesday as he looks to buy time for his diplomatic efforts.

During a delicate stage in the talks with that country, the administration is trying to head off efforts to amend the Defense authorization bill on the Senate floor this week with new sanctions language.

“It’s the president’s view that it’s the right thing for Congress to do to pause so that we can test whether or not the Iranians are serious about resolving this issue diplomatically,” White House Press Secretary Jay Carney told reporters Monday.

Obama will meet Tuesday with Senate leadership and the chairmen and ranking members of the Banking, Foreign Relations, Armed Services and Intelligence committees ahead of nuclear talks later this week in Geneva.

Carney said that halting the progress of Iran’s nuclear program in the first phase of talks would be important, and that anything Iran gets in return would be “reversible” in the next round of talks. He said reports of $40 billion to $50 billion in sanctions relief were “significantly exaggerated.”

Carney noted Obama’s policy that Iran will not be allowed to have a nuclear weapon, but he said it would be preferable to find a peaceful way to achieving that, and he warned again about the risk of war.

“Whether you’re proactively choosing the use of force as the better alternative or simply disallowing or suggesting there’s no path through which you can negotiate a diplomatic, peaceful resolution, you’re still — you’re still leaving yourself with only one other means to achieve that objective, prevent Iran from acquiring a nuclear weapon,” Carney said.

Republicans in particular have been highly suspicious of the Iran talks, with Sens. Marco Rubio of Florida, Mark S. Kirk of Illinois, John Cornyn of Texas and Kelly Ayotte of New Hampshire firing off a letter last week saying the deal in the works seems to be less than advertised.

“In short, the American people will facilitate the payment of $20 billion in hard currency to the world’s leading sponsor of terrorism and in return accept a more advanced and dangerous Iranian nuclear infrastructure,” they wrote.

The senators are seeking that, under any deal, Iran stop enriching uranium, stop work on the Arak heavy water reactor, stop making centrifuges and require Iran to provide access and information to international monitors.