(Reuters) - Senate Republicans on Sunday pressed their demand that the U.S. Congress be allowed to vote on a nuclear agreement with�Iran, but signaled they are willing to wait for last week's interim agreement to be finalized before passing judgment.

"Look, the president needs to sell this to the American people, and Congress needs to be involved," said Senator Bob Corker, chairman of the Senate Foreign Relations Committee.

Corker did not condemn the framework deal reached by�Iran�and major powers in Switzerland on Thursday after months of negotiations, but he cited concerns over inspection provisions and differing accounts from Washington and Tehran over what was actually agreed.

The Tennessee Republican said his committee will go ahead with a planned April 14 vote on legislation requiring President�Barack Obama�to submit a final nuclear agreement to Congress for review and approval. The deal reached last Thursday is supposed to be the framework for a final agreement to be struck by the end of June.

The bill, supported by both Republicans and many Democrats, would prohibit Obama from suspending sanctions on�Iran�during a 60-day congressional review. In that period, Congress could approve or disapprove the agreement, or take no action.

Corker told Fox News on Sunday that he had backing from key Democrats for the bill, including New York Senator Chuck Schumer, a prominent Jewish lawmaker who is line to be the new Senate Democratic leader in early 2017.�Israel�has been strongly critical of the nuclear deal.

Corker acknowledged he did not know if backers of the legislation in the Senate would have the 67 votes needed to override an expected veto by Obama, who says passing the measure would undermine the negotiations with�Iran.

"I don�t know if we have 67 votes. ... We have 64 or 65 that we are aware of today. There are many more that are considering this," Corker said.

In an interview with the New York Times published on Sunday, Obama sought to avoid confrontation with Corker and said he hoped a compromise could be reached - but one that would not encroach on presidential prerogatives.

"I do think Senator Corker ... is somebody who is sincerely concerned about this issue and is a good and decent man, and my hope is that we can find something that allows Congress to express itself but does not encroach on traditional presidential prerogatives � and ensures that, if in fact we get a good deal, that we can go ahead and implement it," Obama said.

DEMOCRATS HOLD THE KEY

With Republicans mostly united on the issue, and some, including potential 2016 presidential candidates, fiercely condemning the deal, the key role likely will be played by lawmakers from Obama's Democratic Party.

Many do not trust�Iran�and fear the verification measures are not adequate. They face energetic lobbying by�Israel, whose prime minister, Benyamin Netanyahu, says the deal as currently configured threatens his country's security.

While many Democrats are skeptical of�Iran, they may be unwilling to hand the U.S. president a major foreign policy defeat.

"Wavering Senate Democrats have been circumspect about the deal reached in Switzerland," said Daniel Harsha, a former Democratic staffer on the House Foreign Affairs Committee.

Until the agreement is finalized and Secretary of State John Kerry testifies about it on Capitol Hill, "you aren't likely to see many Senate Democrats, even those who have publicly backed new sanctions legislation ... publicly pan the agreement," said Harsha, now at Harvard University's Kennedy School.

The agreement reached in Lausanne, Switzerland, would ease economic sanctions on Tehran in return for strict limits on its nuclear sites, centrifuges that can enrich uranium and enriched uranium stockpiles.

Both Corker and Senator Lindsey Graham, a South Carolina Republican, previewed another possible Republican strategy.

If the final agreement with�Iran�is flawed, they argued, it would be better to keep in place an initial interim deal reached with�Iran�in November 2013, which contains limits on Tehran's ability to enrich uranium that could be used for a nuclear weapon. All sides believe that is being observed.

"That's one way of looking at this program - keeping the interim deal in place that's been fairly successful, and have a new crack at it with a new president," Graham said on CBS' Face the Nation program.

Even if this strategy were adopted by the United States, however, it was unclear how it would play with the five other powers engaged in the negotiations with�Iran�- Britain,�China,France,�Germany�and�Russia.

By Reuters