Senators Press Obama for a Tougher Iran Nuclear Deal WASHINGTON - A bipartisan group of senators formally urged the Obama administration on Tuesday to reject any deal with Iran that did not include a tangible rollback of Tehran's nuclear program, as lines hardened ahead of a new round of nuclear talks scheduled for this week in Geneva. The letter was released just hours after a meeting at the White House at which President Obama pleaded personally with senior senators to give Secretary of State John Kerry and his negotiating team time to reach an accord before moving forward with legislation imposing a tough new round of sanctions on Iran. In their letter, the senators said they would not seek to amend a military policy bill now under consideration in the Senate with any provision adding sanctions. But their letter made it clear that opposition was forming to any deal that would loosen some economic sanctions on Iran in exchange for a temporary freeze on the nuclear program. "It is our belief that any interim agreement with the Iranians should bring us closer to our ultimate goal, which is Iran without a nuclear weapons capability," the senators wrote. We must ensure that the steps we take in the coming weeks and months move us towards a resolution that ultimately brings Iran in compliance with all relevant United Nations Security Council resolutions, seeks to prevent Tehran from possessing any enrichment or reprocessing capability, and resolves any and all fears that Iran will develop a nuclear weapons capability. The signers included Charles E. Schumer of New York, the third-ranking Democrat; Robert Menendez of New Jersey, a Democrat who is the chairman of the Senate Foreign Relations Committee; Lindsey Graham, Republican of South Carolina; John McCain, Republican of Arizona; Bob Casey, Democrat of Pennsylvania; and Susan Collins, Republican of Maine. The ranking Republican on the Foreign Relations Committee, Senator Bob Corker of Tennessee, said after the two-hour White House meeting that he remained deeply skeptical of any interim deal with Iran, despite Mr. Obama's plea to give diplomacy a chance. "There's concern that we're giving up some leverage," said Mr. Corker, who likened a deal to previous agreements with North Korea in which Pyongyang was granted relief from sanctions but later reneged on promises to curb its nuclear program. "I think the concern is, whatever you do on the interim basis becomes the new norm," Mr. Corker told reporters after emerging from the meeting at the White House. Mr. Obama's meeting with leaders of the Senate's top foreign policy and national security committees was his most direct lobbying effort on behalf of his efforts to seal a preliminary deal with Iran. Those efforts have met fierce opposition from Israel, from allies in the Persian Gulf and from Republicans and some Democrats in Congress who have sought to impose a new round of sanctions on the Tehran government. The White House said Mr. Obama asked the senators for patience, arguing that "new sanctions should not be enacted during the current negotiations." If Iran does not agree to an interim deal or reneges on its promises, said the White House press secretary, Jay Carney, the president believes it would be appropriate for Congress to move ahead. Mr. Carney said the president also "dispelled" the rumor that a deal would give Iran sanctions relief worth between $40 billion and $50 billion, which he said was "inaccurate." He did not provide an alternative figure, though administration officials have said it is closer to $5 billion. Several senators are backing new sanctions as amendments to a military funding bill. But Mr. Corker said the Senate, for procedural reasons, would not vote on any Iran-related amendments before Thanksgiving, assuring that the next round of negotiations, in Geneva this week, would proceed without the shadow of congressional action. "The president has asked for some time for it to be negotiated, and see if Iran will live up to its obligations," Mr. Corker said, adding that the White House did not suggest that a deal was a "fait accompli." The president, Mr. Corker said, offered the senators a detailed preview of the interim deal that the United States and other major powers are seeking in Geneva. Administration officials said it would grant limited relief from sanctions in return for a six-month freeze on most of Iran's nuclear activities. Critics say that once the sanctions are lifted, they will be extremely difficult to reinstate, and that Iran has only agreed to concessions that would halt its drive to a nuclear weapon by less than a month. But administration officials say they fear that new sanctions would derail the talks, at a time when Iran appears more disposed toward a deal than it has for a decade.