President Trump is expected to “decertify” the Iran nuclear deal this week. The move might seem like the start of a conflict with Tehran, but it really would just force members of Congress to duke it out over the merits of the deal and decide whether they are willing to rip it apart.

It might be a Goldilocks strategy on Trump’s part: an effort to reap the political benefits of rejecting the agreement without incurring the diplomatic costs of actually unraveling it. But in the end, it could well leave Trump and the GOP Congress further damaged for not delivering on their campaign promises.

Certification is mandated by U.S. law and is not part of the terms of the agreement itself, so all a presidential decertification does is trigger a 60-day period in which Congress could vote to reimpose sanctions on Iran. Since the U.S. committed to sanctions relief as part of the agreement, reimposing them would likely be seen as a breach of the deal. The Iranians would then decide whether or not to stay in.

In other words, instead of pulling out of the deal outright — which Trump has the authority to do at any time — he would punt the issue to Congress. And Congress is very unlikely to reimpose tough sanctions. So Trump would be setting up yet another high-risk venture for Republican leaders, who would struggle to pass the kind of deal-killing legislation the GOP has made a centerpiece of its agenda.

So why will it be hard to reimpose sanctions? First, it’s important to consider Congress’s options should Trump decertify the deal.

Legally, the president must certify every 90 days that Iran is “transparently, verifiably and fully implementing” the agreement, that the continued suspension of nuclear sanctions on Iran are “proportionate” to Tehran’s reciprocal actions, and that a continuation of these policies is “vital to the national security interests of the United States.” If he doesn’t, the Iran Nuclear Agreement Review Act — a bill passed in Congress before the U.S. adopted the nuclear deal, formally known as the Joint Comprehensive Plan of Action, as a means for Congress to monitor and review the value and effectiveness of the deal over time — calls on congressional leadership to consider “qualifying legislation” on Iran.

The vagueness of this language allows GOP leadership to go down one of two basic paths: 1. propose deal-threatening legislation that slaps sanctions on Iran, or 2. not, by introducing a watered-down measure that amounts to a threat rather than an action, by passing new non-nuclear sanctions unopposed by the other world powers who signed the agreement, or by doing nothing. So right off the bat, legislators have an opportunity to make a symbolic vote against Iran without facing the consequences of ending the deal.

Should Republican leadership choose the first path, it will be hard-pressed to find enough votes to pass a bill that would break the agreement, i.e., one that reimposes nuclear-related sanctions — even though the Iran Nuclear Agreement Review Act specifies that only 50 senators, rather than the standard 60, are needed to pass qualifying legislation, and there are 52 Republicans in the chamber. That’s because the Democrats who are critical of the deal, the Republicans who have reservations about it, and even those GOP hawks who are most incensed by it are already vocalizing support for the second path, even before Trump announces his certification decision. The results of the Senate’s 58-42 vote on a 2015 motion disapproving of the nuclear deal shows just how difficult it will be to get those 50 yes votes on deal-killing legislation.

How the Senate voted on the 2015 nuclear agreement Votes on a legislative amendment that would have prohibited the president from supporting the Iran nuclear deal. There were 58 votes in favor; 60 votes were required to break a Democratic filibuster. REPUBLICANS DEMOCRATS & INDEPENDENTS SENATOR STATE VOTE SENATOR STATE VOTE Lamar Alexander TN ✓ Ben Cardin MD ✓ Kelly Ayotte NH ✓ Joe Manchin WV ✓ John Barrasso WY ✓ Bob Menendez NJ ✓ Roy Blunt MO ✓ Chuck Schumer NY ✓ John Boozman AR ✓ Tammy Baldwin WI Richard Burr NC ✓ Michael Bennet CO Shelley Moore Capito WV ✓ Richard Blumenthal CT Bill Cassidy LA ✓ Cory Booker NJ Dan Coats IN ✓ Barbara Boxer CA Thad Cochran MS ✓ Sherrod Brown OH Susan Collins ME ✓ Maria Cantwell WA Bob Corker TN ✓ Tom Carper DE John Cornyn TX ✓ Bob Casey Jr. PA Tom Cotton AR ✓ Chris Coons DE Mike Crapo ID ✓ Joe Donnelly IN Ted Cruz TX ✓ Dick Durbin IL Steve Daines MT ✓ Dianne Feinstein CA Mike Enzi WY ✓ Al Franken MN Joni Ernst IA ✓ Kristen Gillibrand NY Deb Fischer NE ✓ Martin Heinrich NM Jeff Flake AZ ✓ Heidi Heitkamp ND Cory Gardner CO ✓ Mazie Hirono HI Lindsey Graham SC ✓ Tim Kaine VA Chuck Grassley IA ✓ Amy Klobuchar MN Orrin Hatch UT ✓ Patrick Leahy VT Dean Heller NV ✓ Ed Markey MA John Hoeven ND ✓ Claire McCaskill MO Jim Inhofe OK ✓ Jeff Merkley OR Johnny Isakson GA ✓ Barbara Mikulski MD Ron Johnson WI ✓ Chris Murphy CT Mark Kirk IL ✓ Patty Murray WA James Lankford OK ✓ Bill Nelson FL Mike Lee UT ✓ Gary Peters MI John McCain AZ ✓ Jack Reed RI Mitch McConnell KY ✓ Harry Reid NV Jerry Moran KS ✓ Brian Schatz HI Lisa Murkowski AK ✓ Jeanne Shaheen NH Rand Paul KY ✓ Debbie Stabenow MI David Perdue GA ✓ Jon Tester MT Rob Portman OH ✓ Tom Udall NM Jim Risch ID ✓ Mark Warner VA Pat Roberts KS ✓ Elizabeth Warren MA Mike Rounds SD ✓ Sheldon Whitehouse RI Marco Rubio FL ✓ Ron Wyden OR Ben Sasse NE ✓ Angus King (I) ME Tim Scott SC ✓ Bernie Sanders (I) VT Jeff Sessions AL ✓ Richard Shelby AL ✓ Dan Sullivan AK ✓ John Thune SD ✓ Thom Tillis NC ✓ Pat Toomey PA ✓ David Vitter LA ✓ Roger Wicker MS ✓ Source: U.S. Senate

Democratic opposition

Nearly the entire Senate, 98 members, voted in favor of the Iran Nuclear Agreement Review Act, also known as Cardin-Corker after its Senate co-sponsors. But four Democratic senators — Ben Cardin of Maryland, Joe Manchin of West Virginia, Robert Menendez of New Jersey and Chuck Schumer of New York — opposed the nuclear agreement itself in 2015, joining all Republicans in the 58-42 vote to disapprove of the accord.

Those votes will be crucial during this upcoming review period, and several Democratic lawmakers and aides in both chambers already say they expect the party to unite behind the deal and oppose the reimposition of sanctions. In a demonstration of the unity they are looking to project, 180 Democratic members of the House — including many who originally voted against the deal — on Wednesday sent a letter to Trump opposing more sanctions on the grounds that undermining the deal at home would hurt U.S. credibility abroad.

Two of the four senators who voted in favor of the motion disapproving of the Iran deal are already on record as now opposing efforts to kill it. “I thought the agreement was a bad agreement, but I also said that let’s see once it passed, let’s give it a little time to see if it’s working or not,” Schumer told reporters on Sept. 20.

Schumer, like many Democrats who had misgivings about the nuclear agreement, repeatedly expressed concern about Israel’s security at the time the deal was being crafted. But the pro-Israel camp in Washington has since changed its tune. While the American Israel Public Affairs Committee aggressively lobbied Democrats to vote the deal down in 2015, the group is not calling for decertification or for U.S. withdrawal from the nuclear accord today. Instead AIPAC has urged the administration to fix some of the deal’s provisions, such as those that allow limits on Iran’s uranium enrichment infrastructure to expire over time.

Last month, Cardin joined Schumer in expressing skepticism about scrapping the deal, with Cardin among those who signed a letter to the president questioning the administration’s claim that Iran had violated the “spirit” of the nuclear accord. Manchin and Menendez, for their part, have yet to comment on the president’s decertification strategy and could in theory vote with a Republican majority in favor of deal-killing legislation. But that is hardly a given. Both of them met at the White House with the president’s national security adviser, H.R. McMaster, earlier this week, and claimed that even he is wary of a full withdrawal.

Not much has changed in public opinion since 2015, when Americans were first presented with the nuclear accord. A plurality still believe it’s a bad deal. But one thing is new: A majority now disapprove of ripping it up.

Public opinion on the Iran deal Responses to polls about the Iran nuclear agreement since 2015 More Americans disapprove of the Iran nuclear agreement than support it … POLLSTER END DATE SUPPORT OPPOSE DON’T KNOW/OTHER Fox News 4/25/2017 35% 42% 23% Quinnipiac University 9/21/2015 26 58 16 Pew Research Center 9/7/2015 21 49 30 Quinnipiac University 8/25/2015 25 55 20 Quinnipiac University 7/28/2015 28 57 15 Pew Research Center 7/20/2015 33 45 22 … but they also disapprove of the US withdrawing from it POLLSTER END DATE APPROVE DISAPPROVE DON’T KNOW/OTHER Pew Research Center 3/15/2017 39% 53% 8% ABC News/Washington Post 1/15/2017 37 46 17

Republican opposition

There are also skeptics of withdrawal within Republican ranks — beyond the president’s national security adviser, secretary of defense and secretary of state — including several of those who were most vocally opposed to the formulation of the agreement and even the one who co-wrote the law outlining the certification requirement in the first place: Bob Corker of Tennessee.

“We gave up all of our leverage already,” Corker said in July, referring to his view that former President Barack Obama’s administration made too many concessions during the original negotiations. “Wait until you have your allies aligned with you. Radically enforce it. If you radically enforce it, they’re liable.”

Other foreign policy pragmatists, such as John McCain of Arizona and Susan Collins of Maine, are similarly skeptical of the prospect of reimposing sanctions. And so too are the Senate’s isolationists, Rand Paul of Kentucky and Jeff Flake of Arizona. “If they’re complying with it, I think we should stay in it,” Paul asserted. Flake agreed, telling reporters last week: “I don’t think we should relieve Iran of its obligations.”

Even Tom Cotton of Arkansas, one of the most aggressive hawks on Iran in Congress, said that Trump should use decertification as a tool of diplomatic leverage with the world powers who signed the deal alongside the U.S. “I have no intent to immediately introduce legislation to snapback all sanctions or to advocate for that,” Cotton told The Wall Street Journal in an interview.

The message from these GOP senators is consistent with that of Democrats who once joined them in opposing the agreement: The deal remains flawed, but only with trust and credibility among America’s foreign allies can Trump reasonably hope to fix it. A deal-threatening sanctions bill would thus face unified Democratic opposition and at least six skeptical Republicans, leaving its passage four votes short out of the gate. The math could get easier if a Democrat or two broke ranks, but more likely, it will only get harder, given the diversity of foreign policy thought already represented among Senate Republicans.

Corker has said he has been working “hand-in-glove” with the Trump administration on its current decertification strategy, and the senator’s aides say he is willing to rewrite parts of the act to free the White House of the legal responsibility and political headache of verifying Iran’s compliance every 90 days. After a Twitter spat between the two men over the weekend, in which Trump criticized Corker for his original role in the Iran deal and Corker returned fire in a New York Times interview, it remains to be seen whether the senator will continue to be so helpful. But regardless of his feelings toward Trump, Corker is still likely to support the goal of sending a message to Iran and the world without taking excessive risk.

Cotton put it bluntly in a speech before the Council on Foreign Relations this week: “Congress and the president, working together, should lay out how the deal must change,” he said, “and if it doesn’t, the consequences Iran will face.”

Trump can still kill the agreement on his own if he has the desire and political will, but there’s no evidence that he does — or that Congress wants to do it for him. At best, the Trump administration can hope that this move will provide the president with leverage in his effort to re-engage international parties on the most worrisome provisions of the agreement. At minimum, Trump will have found a political off-ramp from his campaign promise to kill the deal outright.

CLARIFICATION (Oct. 9, 3:40 p.m.): A previous version of this story was unclear about whether Sen. Ben Cardin or Sen. Chuck Schumer signed a letter to President Trump last month. Cardin signed the letter.