WASHINGTON — Senate Foreign Relations Chairman Bob Corker said Friday he would introduce legislation to fix “major flaws” in the Iran nuclear deal — a step he says will eventually solidify and strengthen the agreement even as President Trump moves to disavow it.

The Tennessee Republican’s proposal came as Trump announced that he would not certify Iran’s compliance with the multi-lateral agreement, negotiated in 2015 by the U.S. and five other countries to prevent Iran from getting a nuclear weapon.

Trump’s move leaves the Iran deal in place — for now — and shifts the spotlight to Congress. Trump asked lawmakers to address what he says are weaknesses in the deal, and Corker’s proposal appears designed to respond to that request.

“We have provided a route to overcome deficiencies and to keep the administration in the deal,” Corker told reporters in a conference call Friday. "And actually make it the kind of deal that it should have been in the first place."

Whether Corker's proposal can pass a deeply divided Congress, and whether it's workable for Congress to try to renegotiate the multi-lateral nuclear accord, is murky at best.

Democrats denounced Trump's decision on Friday as a dangerous move that would undermine U.S. national security and alienate America's most important allies.

"Today’s decision is reckless and dangerous," Maryland Sen. Ben Cardin, the top Democrat on the Foreign Relations Committee, said in an interview with USA TODAY.

In a statement, Cardin said that instead of outlining a serious Iran policy, Trump made a "political decision" that will make it harder for the U.S. to address other threats posed by Iran by imposing "self-inflicted international isolation on the United States."

Senate Minority Leader Chuck Schumer, D-N.Y., noted that Trump went against the advice of his own secretary of Defense and chairman of the Joint Chiefs of Staff in refusing to certify Iran's compliance.

The top two Republicans in Congress both applauded Trump's move and said they were committed to working with the Trump administration to beef up the Iran deal.

“I support President Trump’s decision to reevaluate this dangerous deal, and the House will work with his administration to counter Iran’s range of destabilizing activities," said House Speaker Paul Ryan, R-Wis.

Senate Majority Leader Mitch McConnell, R-Ky., said the president’s decision would allow Congress to strengthen accord and send a signal to U.S. allies that “more work must be done to contain Iran’s malign behavior.”

Other congressional Republicans, many of whom blasted the Iran deal when it was unveiled in 2015, also welcomed Trump's move, even as they quietly fretted about the fallout.

"The President’s announcement today rightly focuses on the full range of deadly threats from the Iranian regime," House Foreign Affairs Chairman Ed Royce, R-Calif., said in a joint statement with other leading GOP lawmakers. "We cannot allow such a regime to become a nuclear power. The nuclear deal has significant flaws that must be addressed if that objective is going to be accomplished."

Earlier this week, Royce urged Trump to stay in the pact, despite its flaws, saying the U.S. should "enforce the hell" out of it instead of abandoning it.

Corker's proposal, which he is drafting with Sen. Tom Cotton, R-Ark., would automatically reimpose U.S. sanctions on Iran if it hits a "breakout period" of being able to build a nuclear weapon in less than a year. Sanctions would also go back into effect if the country violates "enhanced and existing restrictions on its nuclear program," according to a summary provided by Corker's office.

The measure would nix the "sunset" provisions in the current agreement, which critics say will allow Iran to quickly ramp up its uranium enrichment program starting in 2024. By 2031, year 15 of the deal, all the restrictions in the agreement will expire, which Corker and others fear would put Iran on the brink attaining a nuclear weapon.

Corker said his bill, which he plans to introduce as early as next week, would essentially make the Iran nuclear accord permanent, thus preventing Iran from restarting its nuclear program. It would also strengthen the ability of the International Atomic Energy Agency to verify Iran’s compliance with the agreement and limit Iran’s current centrifuge program, which Corker and other critics fear Iran could use to shorten the time it needs to produce a nuclear weapon.

"It's stringent," Corker said. "It assures people that the Iranian program will never move beyond" its current state.

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Sen. Chris Coons, a Delaware Democrat who also sits on the Foreign Relations Committee, expressed support for fixing the Iran agreement, which he agreed has flaws.

But in an interview Thursday with NBC, Coons said he fears that some Republicans maybe “tempted” to jettison the deal entirely and instead reinstate punitive sanctions on Iran that would prompt the country to walk away from any negotiations.

Coons said Iran is in compliance with the agreement and Trump's decision to decertify the deal throws a “hand grenade in the lap of Congress.”

Corker said he has been working closely with Secretary of State Rex Tillerson, as well as Senate Democrats, to craft the proposal. But he said it will be critical for the Trump administration to convince America's European allies, who are a party to the Iran agreement, that this beefed-up extension of the agreement is also in their interest.

"The most important component of this is our European allies," he said. "Tillerson understands that."

Cardin said he had only seen a preliminary outline of Corker's plan, and he said Democrats would not support anything that violated the terms of the current Iran accord. He said the president, not lawmakers, should be leading any renegotiation.

"Congress can't do it. We're not the negotiating team," he said.

Whether Corker and Trump can work together to push this proposal through Congress is unclear. The two men have been engaged in an unusually personal and public spat, lobbing sharp insults at each other last weekend.

In an interview with The New York Times on Sunday, Corker suggested that Trump was reckless and irresponsible. He said Trump’s threatening statements toward other countries could put the U.S. “on the path to World War III.” The bitterness continued this week, as White House spokeswoman Sarah Huckabee Sanders on Thursday claimed, falsely, that Corker worked with top Democrats “to pave the way” for the Iran deal.

Corker did not address his ruptured relationship with Trump in Friday's call, telling reporters he wanted to focus on the Iran policy. But he said the situation was "very fluid" and he would work with "responsible individuals within the administration."

It's not clear what will happen if Congress fails to act before Trump faces the next certification deadline in mid-January. On Friday, the president threatened to walk away from the deal if lawmakers didn't fix it.