An earlier version of this article misidentified the state of Sen. Dan Sullivan. He represents Alaska. This version has been corrected.

President Trump is expected to announce next week that he will "decertify" the international nuclear deal with Iran, saying it is not in the national interest of the United States and kicking the issue to a reluctant Congress, people briefed on the White House strategy said Thursday.

The move would mark the first step in a process that could eventually result in the resumption of U.S. sanctions against Iran, potentially derailing a deal limiting Iran's nuclear activities reached in 2015 with the United States and five other nations.

But Trump would hold off on recommending that Congress reimpose sanctions, which would constitute a clearer break from the pact, according to four people familiar with aspects of the president's thinking.

The decision would amount to a middle ground of sorts between Trump, who has long wanted to withdraw from the agreement completely, and many congressional leaders and senior diplomatic, military and national security advisers, who say the deal is worth preserving with changes if possible.

This week, Defense Secretary Jim Mattis and Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff, expressed qualified support for the deal during congressional testimony. And Mattis suggested he did not believe taking the step to decertify would scuttle the agreement.

Trump is expected to deliver a speech, tentatively scheduled for Oct. 12, laying out a larger strategy for confronting the nation he blames for terrorism and instability throughout the Middle East.

Officials cautioned that plans could still change, and the White House would not confirm plans for a speech or its contents. Trump faces an Oct. 15 deadline to report to Congress on whether Iran is complying with the agreement and whether he judges the deal to be in the U.S. national security interest.

"The administration looks forward to sharing details of our Iran strategy at the appropriate time," said Michael Anton, spokesman for the White House National Security Council.

The fate of the nuclear pact is only one consideration in that larger strategy, U.S. officials said, although given Trump's focus on the deal as an "embarrassment," it is the most high-profile element.

The agreement signed under President Barack Obama was intended to close off the potential for Iran to quickly build a nuclear bomb by curbing nuclear activities the United States and other partners considered most troubling. It allowed some uranium enrichment to continue for what Iran claims is peaceful medical research and energy; the country says it has never sought nuclear weapons. In exchange, world powers lifted crippling U.S. and international economic sanctions.

At issue now is the fate of U.S. sanctions lifted by Obama and, by extension, whether the United States will move to break the deal. That could open an international breach with European partners who have warned they will not follow suit.

Outreach for a "transatlantic understanding" about reopening or supplementing the deal is likely to be part of Trump's announcement, according to one Iran analyst who has discussed the strategy with administration officials. Several other people familiar with a nine-month review of U.S. military, diplomatic, economic and intelligence policy toward Iran spoke on the condition of anonymity because aspects of the policy are not yet set, and Trump has not announced his decision.

Trump said last month that he had decided what to do on Iran but that he would not divulge the decision at that time.

Welcoming military leaders to a White House dinner Thursday night, Trump said Iran had not lived up to its end of the nuclear bargain.

"The Iranian regime supports terrorism and exports violence, bloodshed and chaos across the Middle East," he said. "That is why we must put an end to Iran's continued aggression and nuclear ambitions. They have not lived up to the spirit of their agreement."

The president's senior national security advisers agreed within the past several weeks to recommend that Trump "decertify" the agreement at the Oct. 15 deadline, two of those people said.

The administration has begun discussing possible legislation to "strengthen" the agreement, congressional aides and others said — a "fix it or nix it" approach suggested by Israeli Prime Minister Benjamin Netanyahu and Sen. Tom Cotton (Ark.), a leading Republican hawk on Iran.

But the prospects of such an approach are highly uncertain, and many supporters of the deal consider it a dodge.

Iranian President Hassan Rouhani said last month that he will not reopen the agreement for negotiation. Separately, representatives of Iran, China and Russia told Secretary of State Rex Tillerson the same thing during a meeting on the sidelines of the U.N. General Assembly session last month, two senior diplomats familiar with that meeting said.

[U.S., Iran accuse one another of undermining nuclear deal]

Cotton appeared to preview the main elements of the administration's plan this week, although he said he does not know exactly what Trump plans to do. The two met Thursday at the White House.

In a speech Tuesday at the Council on Foreign Relations, Cotton said Trump should "decline to certify the deal and begin the work of strengthening it."

He said decertification should be based on a finding that the deal is not in the U.S. "vital national security interest," citing "the long catalogue of the regime's crimes and perfidy against the United States, as well as the deal's inherent weakness."

But Cotton said he would not push for the immediate reimposition of sanctions, as some conservative lawmakers and outside lobbying groups are doing.

He laid out proposals for Congress to pass new stipulations for U.S. participation in the deal, including elimination of the "sunset clauses" under which restrictions on some Iranian nuclear activities expire after several years, tougher inspections requirements and new curbs on Iran's ballistic and cruise missile programs.

Cotton claimed that a unified statement from Congress would help Trump forge a new agreement among European and other allies and strengthen his hand for renegotiation.

"The world needs to know we're serious, we're willing to walk away, and we're willing to reimpose sanctions — and a lot more than that," Cotton said. "And they'll know that when the president declines to certify the deal, and not before."

In the Senate, plans have been underway for months to respond to a presidential decertification.

Sen. Bob Corker (R-Tenn.), chairman of the Foreign Relations Committee, has been Capitol Hill's point person on discussions with the White House. Sen. Benjamin L. Cardin (D-Md.) and Senate Majority Leader Mitch McConnell (R-Ky.) also have been made aware of plans being discussed with the White House and State Department.

McConnell is not eager to take on the issue at a time when the Senate calendar is full and midterm elections are only a year off, according to congressional aides and a Western diplomat who has met with him.

"He's not excited about getting the 'Old Maid,' " said the diplomat, referring to the card game where the player left holding a certain card is the loser.

Still, Republican leaders say they are confident that they can craft a legislative response to the president's decision that can address deficiencies in the deal and avoid turning the issue into a political litmus test for the GOP.

Some Republicans have also been urging the president to take a critical public stance against the deal — without blowing it up.

"The president should come out and say, 'Hey, we're going to enforce this, and right now I think these different provisions are being violated,' " Sen. Dan Sullivan (R-Alaska) said last week, adding that Trump should tell Iran it has a limited window to fix problems. "If they don't, do what [then-Secretary of State] John Kerry and Barack Obama said they were going to do, which is snap back sanctions."

Rep. Adam B. Schiff (D-Calif.) said a decertification would undermine global confidence in the deal and in U.S. commitments generally.

"If the president fails to certify the deal while saying Iran is complying with it, it's a destructive political gesture," Schiff said.

[Text of Iran nuclear deal]

Sen. Dianne Feinstein (D-

Calif.) said that beginning a process that could result in the United States withdrawing from the Iran deal would go against "advice from his own national security team and our closest allies."

"Unilaterally abandoning this agreement will make the world less safe," she said in a statement.

A half-dozen Democrats who went to the White House on Wednesday evening to meet with national security adviser H.R. McMaster came away with the impression that he agreed with Mattis and Dunford.

The group who visited with McMaster to discuss Iran included Cardin and Sens. Robert Menendez (D-N.J.), Christopher A. Coons (D-Del.), Joe Manchin III (D-W.Va.), Heidi Heitkamp (D-N.D.) and Angus King (I-Maine), according to a person familiar with the meeting.

Sen. Cory Gardner (R-Colo.) called the nuclear deal "very, very flawed" but not completely ineffective — a common view among Republicans and a potential starting point for negotiations with Democrats.

"What we have to figure out is how to actually accomplish what we were well on our way to do before Barack Obama gave them a patient pathway to a nuclear bomb," Gardner said, referring to what he and other Republicans see as the deal's failure to prevent Iran from developing weapons down the road.

Those concerns are one of the main areas that Republicans are planning to address in their legislative response to the president's decision, according to a person familiar with plans being hammered out between the White House, State Department and Capitol Hill.

Abby Phillip and Ed O'Keefe contributed to this report.