Democrats won’t back Iran nuclear deal in blow to White House as enough break with Obama to to put veto-proof legislation in the works to stop an agreement

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Democratic senators remain irritated with their GOP colleagues who last week sent a letter to Iranian leaders undercutting President Barack Obama, but they will still back bipartisan legislation that would give Congress final say over a nuclear deal.

Enough members of the president's party have signaled support for that bill and another that would impose new sanctions on Iran if it doesn't make an agreement with negotiators that the White House would be powerless to stop the measures from going into effect once passed.

The Obama administration and its international partners now have until March 24 to set up the framework for a deal. 

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Senate Foreign Relations Committee Chairman Bob Corker, a Republican, center, is flanked by the committee's ranking member, Sen. Robert Menendez, a Democrat, right, and Sen. James Risch, a Republican, as they listen to Secretary of State John Kerry, center, back to camera, testify on Capitol Hill last week. Corker and Menendez are the chief sponsors of one of the bills that would restrict the executive branch's negotiating authority

After that, a dozen Democratic senators, including Richard Blumenthal of Connecticut, Heidi Heitkamp of North Dakota and Robert Menendez of New Jersey, the highest-ranking Democrat on the Senate Foreign Affairs committee, have said they will join with the GOP majority to pass bills inserting themselves into the process.

One would levy additional sanctions on Iran after June 30 if it doesn't agree to the final terms of a deal, though monthly waivers would be allowed should more time be requested. The other would give the Senate the power to reject within 60 days any pact the executive branch makes with Iran.

Democrats who spoke with Politico voiced their displeasure with the 47 GOP senators who wrote a letter to Iran notifying the country's leaders that any contract it makes with the Obama administration would be nullified when a new president takes office in January 2017, whereas most members of the upper chamber would be in office for years to come. 

But that hasn't changed their position on the core issue, they've said.

'The letter’s incredibly unfortunate and inappropriate,' Heitkamp said.'That doesn’t diminish my support for the legislation that we introduced.'

Michigan Sen. Gary Peters similarly said the missive was 'simply unacceptable' and 'brought hyperpartisanship to an issue that we need to maintain our bipartisanship in.'

He added: 'That doesn’t change my support for that bill. … I stay firm.' 

Blumenthal last week called Republicans' actions 'unconscionable' and bemoaned them for disrespecting the president. 

At the time, he said the bipartisan coalition of senators willing to buck the White House was 'in tatters.' Blumenthal told CNN that he was determined to 'stitch it back together,' though.

A week later it appeared that the group was holding strong and that Senate Foreign Relations Bob Corker, one of just seven Republican senators who did not sign the 'open letter,' was correct in predicting last Thursday that the whole thing would blow over.

'Let a couple days go by. We think there’s going to be really ignited momentum,' Corker had told Politico. Nobody’s dropping out. We’ve had reaffirmed commitment.'

Democratic senators remain irritated with their GOP colleagues who last week sent a letter to Iranian leaders, but they will still back bipartisan legislation that would give Congress final say over a nuclear deal. Freshman Sen. Tom Cotton of Arkansas, pictured here last Wednesday on Capitol Hill, authored the missive to Tehran

Meanwhile, Republicans who did sign the letter triumphantly declared on the Sunday news shows that they had no 'regrets' about sending Tehran the strongly worded message. 

'I stand by the letter,' National Republican Senatorial Committee Chairman Rodger Wicker said on NBC's Meet the Press.

'I think it's interesting that we've had so much talk about process, just like we've had talk about process with Prime Minister Netanyahu's speech, rather than dealing with the substance,' the Mississippi Republican asserted, referring to House Republican leadership's end run around the White House earlier this year when it invited Israeli PM Benjamin Netanyahu to address Congress. 

Senate Majority Leader Mitch McConnell told CNN he thinks it was 'fair' for Republicans to explain that Congress will be involved in the process one way or another.

'I don’t think it was a mistake,' he said of the message to Tehran.

'The administration would like to have a distraction, but the point is the subject of the matter,' the GOP leader said. 

'Apparently, the Obama administration is on the cusp of entering into a very bad deal with one of the worst regimes in the world.'

Arkansas Sen. Tom Cotton, the author of the GOP letter, said on CBS' Face the Nation that 'Iran’s leaders needed to hear the message loud and clear.'

'I can tell you they are not hearing the message from Geneva,' he told show host Bob Schieffer.

Secretary of State John Kerry, who has primarily led talks with Tehran on behalf of the U.S., lambasted letter signers on Sunday, saying, 'I’ve never seen anything like this.'

Kerry, a former Massachusetts senator, warned that negotiations would likely extend beyond the end of the month. 

'We believe very much that there’s not going to be anything that’s going to change in April or May or June that suggests that a decision you can’t make now will be made then,' he said in a separate appearance on Face the Nation.

Secretary of State John Kerry, who has primarily led talks with Tehran on behalf of the U.S., warned Sunday that negotiations would likely extend beyond Democrats' deadline for an agreement framework- March 24

The White House has threatened to veto Senate legislation interfering with the administration's attempt to convince Tehran to put aside its nuclear ambitions. 

Obama's chief of staff Denis McDonough again told Corker, a sponsor of the 60-day review bill along with predecessor Menendez, in a Saturday note that the president would not sign legislation usurping his ability to unilaterally approve these types of agreements with foreign governments.

McDonough said in the letter to Corker that the White House has 'welcomed Congress’ important role' in talks before essentially instructing the legislative branch to butt out.

The Corker-Menendez legislation 'goes well beyond ensuring that Congress has a role to play in any deal with Iran,' McDonough contended, and could set a 'potentially damaging precedent.'

On Monday, the White House reiterated its stance that Congress has thoroughly been consulted during negotiations and vowed to continue involving the legislature when the time comes to talk about removing sanctions on Iran.

Claims to the contrary are 'baloney,' the president's spokesman, Josh Earnest, said, 

Earnest said that legislation giving Congress 60 days to reject a deal would suggest to the Iranians that the United States may not stick to its end of the bargain.

'We can't have a situation where you have people in the Congress back seat driving,' the Obama administration official said.

If Democrats and Republicans in the Senate stick together, the White House will not be able undo their work. Supporters of the bills now number in the mid 60s. A vote of 66 lawmakers or more in favor of the measures would tie the president's hands.

Virginia Sen. Tim Kaine said Sunday it was 'unrealistic' for the White House to think that Congress wouldn't have a say in any dealings with Iran, however.

'I have supported the negotiations to this point, but any deal that touches upon the congressional statutory sanctions is gonna get a review of Congress, and the only question is are you going to have a constructive, deliberate bipartisan process, or are you going to be rushed and partisan,' he said on Meet the Press.