Jonathan Ernst/Reuters

Congress has won its right to have a say—if it wants—on the Obama administration's potential nuclear agreement with Iran.

The White House on Tuesday said President Obama would sign compromise legislation giving Congress the opportunity to review—and potentially reject—a final deal before any sanctions get waived. The move defuses a standoff over the separation of powers that could have led Congress to override a presidential veto on foreign policy legislation for the first time in three decades. The Senate Foreign Relations Committee approved the revised legislation on Tuesday afternoon, and with strong bipartisan support, it appears likely to pass both chambers of Congress in the next several weeks.

If the administration can finalize its deal with Tehran by the end of June, lawmakers would have 30 days to approve it, disapprove it, or take no action—in which case the agreement would take effect. That window has been shortened from 60 days in the original proposal from Senators Bob Corker, a Tennessee Republican, and Bob Menendez, a New Jersey Democrat. The bill also changes a requirement that the administration regularly update Congress on Iran's support for terrorist groups, which the White House opposed. Those changes helped solidify Democratic support in the face of a veto threat from the White House, and in exchange, the bill will now prohibit the administration from waiving any nuclear sanctions on Iran until after Congress has the chance to review the agreement. Congress will also have to vote to permanently lift the sanctions once the administration certifies that Iran is complying with the agreement to limit its nuclear activities.

Josh Earnest, the White House press secretary, told reporters that while Obama was "not particularly thrilled" with the legislation, it had "undergone substantial revision such that it’s now in the form of a compromise that the president is willing to sign." In other words, the White House is relenting because after years of skirmishing over the limits of executive power, Congress has finally forced the president's hand. With congressional Democrats supporting the Senate plan, Obama faced the prospect of an embarrassing veto fight that itself could have scuttled the negotiations with Iran.

Instead, administration officials on Tuesday afternoon assured their allies on Capitol Hill that the revised bill would not undermine the talks. Senator Barbara Boxer said that while she believed the original proposal would "disrupt and upend" the negotiations, "I believe this new bill will not do that." The Foreign Relations Committee unanimously approved the new proposal on Tuesday afternoon after Republicans on the panel held off on offering amendments that Democrats vowed to oppose. That included Marco Rubio, the Florida Republican and newly-minted presidential candidate who had wanted language added to force Iran to recognize Israel as part of any agreement.

The revised legislation does nothing to diminish the Republican opposition to Obama's framework agreement with Iran, but even Democrats said the main issue was whether the administration could cut Congress out entirely on such an important international accord. "We're involved here. We have to be involved here," said Senator Ben Cardin of Maryland, who replaced the indicted Menendez as the top Democrat on the Foreign Relations Committee.

In forcing its way into the Iran debate, Congress has succeeded where more partisan efforts to restrain the Obama White House have failed in recent years, most notably on immigration. Yet because of the way the Corker bill is written, it will be much harder for lawmakers to actually reject an Iran deal than it was for them to guarantee their opportunity to do so. Maintaining that consensus once the administration returns with a final agreement will be a much taller task.

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