WASHINGTON – President Donald Trump will not withdraw from the Iran nuclear deal, but he will decertify that Iran is meeting the terms of a separate U.S. law directing the country to forgo its nuclear weapons, Secretary of State Rex Tillerson said.

“The intent is that we will stay in JCPOA – but the president is going to decertify under INARA,” Tillerson said in a phone call in advance of the announcement.

Tillerson was referring first to the Joint Comprehensive Plan of Action, an multinational agreement reached in July 2015 directing that Iran’s nuclear energy program would be for peaceful purposes only. As a candidate and as president, Trump has repeatedly argued that the deal was too weak and would be replaced.

The second agreement is the Iran Nuclear Agreement Review Act, which Congress passed in May 2015 to provide oversight of the Iran nuclear deal. It requires the president to certify every 90 days that Iran is in compliance with the JCPOA.

Trump has previously certified that Iran was in technical compliance, but remained unsatisfied with the JCPOA’s limited scope and terms of sanctions relief, Tillerson said.

In the last several months, leadership from the State Department, Treasury, intelligence agencies and defense have worked on an alternative approach, Tillerson said. Under Trump’s proposal, he plans to decertify that Iran has met the terms set for sanctions relief, which will then spur three possible outcomes.

First, Congress could choose not to act on the decertification, in which case the JCPOA remains unaffected. It could choose to levy sanctions against Iran – which would void the JCPOA. Third, Tillerson said, the president’s preferred option is for Congress to amend INARA to have it address a more comprehensive approach to Iran – including adding what he called “triggers” that would automatically generate sanctions if violated, instead of having to them return to Congress for a vote on sanctions, as they will now.

“The president has come to the conclusion that he cannot certify under INARA that the sanctions relief that was provided is proportionate to the effective benefit that we are seeing,” Tillerson said.

Trump would like Iran’s ballistic missiles program and its destabilizing activities - such as supporting Houthi fighters in Yemen - to be part of what is considered in an amended INARA.

The proposed way forward enables the White House to rework aspects of the Iran nuclear deal from the U.S. side without immediately risking that the current JCPOA will fall apart due to U.S. sanctions - which would allow Iran to restart is nuclear weapons program.

The JCPOA could still fall apart if Congress decides that its plan of action is to impose sanctions instead of pursuing Trump’s preferred route - to renegotiate and pass an amended INARA. Tillerson said Trump would sign an amended INARA into law so it would outlive his term and the terms of the JCPOA.

Tillerson said an alternative approach, such as getting Iran to renegotiate stricter terms of the JCPOA was “unlikely.”

“This is the pathway we think provides us the best platform to attempt fix this deal,” Tillerson said.

The decertification starts a 60-day clock within which Congress may fast-track the reimposition of sanctions lifted under the deal.

Sens. Bob Corker and Tom Cotton reportedly plan to introduce legislation that they say will fix flaws in the Iran nuclear deal—“without violating U.S. commitments,” Corker said in a statement Friday.

A key part of the Corker-Cotton plan, according a summary circulating Friday, would automatically reimpose U.S. sanctions if Iran comes within a year of obtaining a nuclear weapon.

Corker, R-Tenn., chairs the Senate Foreign Relations Committee, and Cotton, R-Ark., chairs the Senate Armed Services Air Land Subcommittee.

The top Democrat on the Senate Foreign Relations Committee, Maryland Sen. Ben Cardin, met with Tillerson earlier this week. Though Cardin voted against the agreement, he has since advocated for staying in it and enforcing it.

“In regards to Iran, the president looks like has made the decision which I think is a wrong decision, is going to compromise America’s national security issues put us in a weaker position on the Iran negotiations. So I think there’s a certainly some disagreements that are going along,” Cardin said on Bloomberg TV Thursday.

The top Democrat on the House Foreign Relations Committee, New York Rep. Eliot Engel, said the action “is a risky gamble” because it weakens an agreement that keeps Iran from building nuclear weapons and harms America’s credibility on the world stage.

“I have to ask: what major power will trust our word on potential North Korean nuclear negotiations, given how Trump is undermining the agreement with Iran?” Engel said in a statement Friday.

Joe Gould in Washington, D.C., contributed to this report.