Sen. Tim Kaine has lined up the votes to adopt a resolution to restrict President Donald Trump’s ability to attack Iran, though a vote on the matter this week would fall short absent a procedural agreement with Republican leadership.

The Virginia Democrat announced Tuesday he received support from at least four GOP senators for using the 1973 War Powers Act to adopt a binding resolution ordering the Trump administration to immediately end all unauthorized military hostilities against Iran and its government. Those senators are Rand Paul of Kentucky, Mike Lee of Utah, Susan Collins of Maine and Todd Young of Indiana.

“We have been able to get some amendments that have earned the support first of Sens. Lee and Paul but now the support also of Sens. Young and Collins, and there are a number of other Republicans who are looking at it as well,” Kaine said. “So now we have the 51 votes that we need for the version that’s the bipartisan version.”

Kaine was referring to the second of two Iran-related resolutions he introduced under the War Powers law. That second bipartisan resolution, filed last week, was modified from an earlier Democratic version introduced in the hours after the Jan. 3 drone strike killing of Iranian Maj. Gen. Qassem Soleimani at Baghdad International Airport.

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It was that killing, and the shifting justifications for it by the Trump administration, that Democrats and a few Republicans worry could still risk a slide toward a shooting war with Iran.

The changes Kaine made to make his resolution more acceptable to Republicans include deleting some language from the findings section. The deleted language related to statements Trump made last June asserting he did not need congressional authorization to initiate military action against Iran and other language criticizing aspects of the administration’s Iran policy.

The bipartisan version of the resolution would require the immediate cessation of attacks on Iran rather than give the administration 30 days, as the original version did, to wind down operations.

But a vote on Kaine’s bipartisan resolution may have to wait, as it will not be eligible until next week under the War Powers Act for an expedited floor vote. War powers resolutions are not subject to filibusters, so only 51 votes are needed for passage.

Once the House sends over impeachment articles to the Senate, as is expected Wednesday, all other legislative business would be placed on hold while senators participate in the impeachment trial of the president. Trump was impeached in December over his efforts to withhold military aid to Ukraine to pressure the Kyiv government to open politically advantageous investigations into former Vice President Joe Biden and son Hunter Biden.

A Senate Democratic staffer, who was not authorized to be named, said in theory an agreement could be reached with Republican leadership to allow the bipartisan resolution to come up for a vote this week, particularly as it now has lined up the minimum necessary support. But Senate Majority Leader Mitch McConnell, R-Ky., has not indicated what he will do.

Though he is supportive of reasserting Congress’ constitutional authority over war declaration matters, Young on Tuesday said he would not support a procedural vote to discharge from the Senate Foreign Relations Committee the first Kaine resolution and then amend it on the floor to make it the second, bipartisan version of the resolution.

“I have been working with Sen. Kaine to revise his resolution away from delivering a politically charged message to instead focus on the important substance that this issue demands,” Young said in a statement. “Unfortunately, due to Senate parliamentarian procedures, those revisions will not be incorporated until after a partisan vote to discharge occurs. … I will be opposing the motion to discharge and hope that we can continue working on this issue in a less politicized manner.”

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Collins said she was ready to co-sponsor the Kaine resolution. “Over the past decade, Congress has too often abdicated its constitutional responsibilities on authorizing the sustained use of military force,” Collins said in a statement. “The Kaine resolution would continue to allow the President to respond to emergencies created by aggression from any hostile nation, including Iran, and to repel an imminent attack by Iran or its proxy forces.  It also does not alter the President’s inherent authority as Commander in Chief to defend our nation and U.S. forces abroad.  It simply makes clear that only the Legislative Branch may declare war or commit our armed forces to a sustained military conflict with Iran.”

In the House, votes on Iran-related measures are expected to be scheduled after lawmakers return from their weeklong Martin Luther King Jr. recess, Rep. Ro Khanna told reporters.

The California Democrat is sponsoring a bill that would prohibit the use of federal funds for any unauthorized military operations against Iran and has been promised a floor vote. Rep. Barbara Lee, D-Calif., has also secured a promise for a floor vote on her bill that would repeal the 2002 Authorization for Use of Military Force against Iraq, which the administration has partially relied on to justify its killing of Soleimani.

“Certainly those two [bills] we’re going to consider soon, and then there may well be others,” House Majority Leader Steny H. Hoyer of Maryland told reporters.