WASHINGTON - President Donald Trump on Friday announced that he will abide by an international nuclear deal with Iran for now, but ask Congress to attach new caveats that could either alter the deal or lead to its rupture.

Trump will withdraw presidential "certification" or endorsement of the agreement negotiated by his predecessor, but will not immediately bust the deal by reimposing U.S. sanctions on Iran's disputed nuclear program.

Trump detailed his dissatisfaction with what he sees as gaps and failures in the agreement within a larger reframing of U.S. policy toward Iran, whose leadership he harshly condemned as a "rogue regime."

"As I have said many times the Iran deal was one of the worst and one sided deals the United States has ever entered into," Trump said, later adding it "was one of the worst and most one-sided transactions the U.S. has ever entered into."

He charged that Tehran is "not living up to the spirit of the deal."

Trump said that if Congress, U.S. allies and his administration cannot come up with way to strengthen the nuclear deal, "it will be terminated.

Trump's compromise gives at least temporary reprieve to an agreement that limits Iran's nuclear activities and opened its economy to greater Western investment, but which does not foreclose the possibility that the Islamic Republic could eventually develop a nuclear weapon.

Iran has repeatedly insisted that it does not seek nuclear arms, but says it will not give up the ability to enrich uranium for energy and research reactors.

Instead of withdrawing outright, Trump asked Congress to amend a law that gives lawmakers some oversight over the deal.

The Trump administration is asking Congress to add conditions for U.S. cooperation that would address Iranian ballistic missile development as well as alleged support for terrorist or extremist groups in Lebanon, Yemen and elsewhere, Secretary of State Rex Tillerson said. The administration also wants to address "sunset clauses" in the deal that allow Iran to resume certain nuclear activities beginning eight years after the deal went into effect in 2015.

Tillerson called that a "countdown clock to when Iran can have a nuclear program again."

These new "trigger points" would draw lines for Iran that are separate from the deal itself, Tillerson said.

If the amendment is approved by Congress and Iran fails to meet the new requirements, the U.S. could impose new sanctions that would effectively break the deal.

Neither Tillerson nor White House national security adviser H.R. McMaster spelled out exactly what the administration's test would be for triggering new sanctions during a briefing for reporters Thursday evening, but Senate Foreign Relations Committee Chairman Sen. Bob Corker, R-Tenn., released a summary of his goals for amending the oversight legislation.

U.S. sanctions would automatically "snap back" into place if Iran gets within one year of being able to achieve a weapon, the summary said.

New restrictions under the legislation would bolster the International Atomic Energy Agency in its effort to verify that Iran is complying with the deal and would "limit Iran's advanced centrifuge program," the Croker statement said.

Those restrictions would "remain in force indefinitely, effectively ridding the JCPOA of its sunset provisions as they apply to U.S. sanctions" - he said referring to the deal by a common acronym.

Corker, in a phone call with reporters, insisted that the plan will not violate the United States' obligations under the deal, because the pact does not give Iran express permission to move toward nuclearization after the deal's restrictions on Iran expire.

"We've taken pains to ensure that we in no way are altering the JCPOA, we're going to honor the terms of the JCPOA," he said. "We're going to honor the JCPOA, but in the event Iran takes steps to move to a lesser place than a one-year breakout . . . we're going to reapply our sanctions."

But he acknowledged that it will be challenging to bring Democrats on board - and stressed that much of the responsibility for seeing this proposal through is in the hands of the president.

Democrats this week stressed that the president's erratic behavior, his insistence on decertifying the Iran deal, and his repeated criticism of the nuclear pact despite his national security team's support for it, make cooperating on any changes impossible.

"The effect of what the president has done has really been to constrain our freedom of action," said Rep. Adam Schiff, Calif., the ranking Democrat on the House Intelligence Committee, "because steps we might have taken to constrain Iran's malevolent activity will now be viewed through the prism of the president's hostility to the nuclear deal."

The new U.S. tests for Iran's compliance with the pact and a potential separate agreement among signers of the deal would be new conditions that "lay alongside" the 2015 agreement, Tillerson said.

Tillerson acknowledged that neither amending the oversight law nor securing a separate new international accord addressing the deal's expiration clauses would be easy to achieve.

He said Trump is "not particularly optimistic," but willing to try.

"We may be unsuccessful. We may not be able to fix it. We may end up out of the deal," Tillerson said. "But I think rather than just walk, he's saying, 'I'm going to try to address some of the issues that I think are deficiencies in the agreement.'"

Trump's address is expected to cover a range of U.S. allegations about Iran, including alleged support for terrorist activities and a ballistic missile program that the United States suspects is tied to a nuclear weapons plan that Iran denies.

Trump has frequently criticized the agreement as weak and unfair to the United States. But he has listened for months as important allies, a majority of his senior national security advisers and many congressional leaders have argued that it retains value for the United States.

The 2015 agreement among the United States, Iran, Britain, France, Germany, Russia and China set limits on Iran's nuclear program in exchange for the lifting of what had become crippling economic sanctions imposed over nuclear development that much of the world feared was aimed at a bomb.

The pact was a signature foreign policy goal of the Obama administration, which considered it a potential building block for a better U.S. relationship with Tehran after more than three decades of enmity.

Critics of the deal say the agreement does not prevent an eventual Iranian bomb and at best merely delays that capability.

The pact as negotiated is limited to Iranian nuclear activity, which the country claims has always been peaceful. Under the agreement, Iran was allowed to keep some uranium-enrichment capacity.

The deal was not designed to address many other areas of international concern, including Iranian missile programs, its alleged support for terrorism and its human rights record. All of those are subject to separate international and U.S. sanctions that are unaffected by the nuclear agreement.

Trump has said that Iran's behavior means it is not living up to the "spirit" of the nuclear accord, although U.S. officials acknowledge that Iran is meeting its technical obligations.

Trump also expressed support for new unilateral and international sanctions on Iran's powerful Revolutionary Guard Corps, but did not brand the group a "foreign terrorist organization." That designation carries legal requirements that could tie United States' hands in other areas, Tillerson said.

Under the oversight law, the president must certify every 90 days that Iran is complying with the deal known as the Joint Comprehensive Plan of Action or JCPOA, and that it remains in U.S. national security interests. Trump has reluctantly made that certification twice before, but balked at doing so at the next deadline on Oct. 15.

Congress now has 60 days to consider whether to reimpose sanctions. Congress could buck the administration's request and slap the sanctions back on now, although some of the leading Iran hawks in Congress have already suggested they could be on board.

House Foreign Affairs Committee Chairman Edward Royce, R-Calif., said earlier this week that rather than scrap the deal, he wants to "enforce the hell out of it."

The Trump administration has worked with Corker and a leading Iran hawk, Sen. Tom Cotton, R-Ark., to come up with a plan for legislation that would set new conditions on U.S. participation in the deal. Cotton has said he will not lead a charge to reimpose sanctions, sending an important signal to other conservatives and outside groups.

"Over the last several months, we have been working closely with the State Department, National Security Council and Senator Cotton to develop a legislative strategy to address bipartisan concerns about the JCPOA without violating U.S. commitments," Corker said in a statement Friday.

McMaster expressed some optimism that the reception on Capitol Hill will be "positive."

"I think in the foreign policy area . . . there should be a lot of ground for bipartisan support for these initiatives and strategies," McMaster added. "So we think we have a real opportunity to apply a legislative remedy to some of the fundamental flaws in the deal involving enforcement as well as pertaining to the sunset clause."

Tillerson added that the administration is hoping that Congress will make a decision on amending the law before the next certification is due in 90 days. The administration would like to remove the certification process altogether, while retaining congressional oversight.

"If it takes longer than that then there's something I don't understand about the deliberation," Tillerson said.

Ben Rhodes, Obama's deputy national security adviser, called Trump's actions "unnecessary and arbitrary."

"If you're most concerned about what will happen in 2025, there's no need to precipitate a crisis in October of 2017 around and arbitrary congressional deadline," Rhodes said. "There's plenty of time to assess how the deal is working, and make decisions around what the United States wants to do."

Rhodes said he believes Trump's plan is rooted in his political campaign promises, and his irritation over having to ratify an Obama priority every 90 days.

"This is entirely over Trump's annoyance with the certification process," he said. "It forces him to certify Iran is complying, the deal is working, and all his bombastic rhetoric about the deal has been based in dishonestly."

Authors Information: Abby Phillip is a national political reporter covering the White House for The Washington Post. Anne Gearan is a national politics correspondent for The Washington Post.