The Senate is expected to pass a measure Thursday limiting President Trump’s ability to act militarily against Iran, in lawmakers’ latest bipartisan attempt to compel the White House to involve them in foreign policy decisions.

Eight Republicans voted Wednesday to advance legislation invoking Congress’s war powers, a move intended to prevent the president from engaging in hostilities against Tehran without explicit authorization from the legislative branch — except in cases of clear self-defense. The vote reflects the frustration with Trump’s decision to kill a top Iranian commander, Qasem Soleimani, without first consulting lawmakers, and with what many on Capitol Hill considered insufficient candor from administration officials who have briefed them in the aftermath.

“No president has the authority to commit our military to a sustained conflict,” Sen. Susan Collins (R-Maine) told reporters, reiterating her support for the measure.

Collins joined Sens. Rand Paul (Ky.), Mike Lee (Utah) and Todd C. Young (Ind.) as the earliest Republicans to commit their support to the measure drafted by Sen. Tim Kaine (D-Va.). They did so only after Kaine agreed to strike references to Trump that appeared in his original draft.

But the legislation — which, as a war powers measure, was guaranteed a vote — languished for the past several weeks while the Senate was singularly focused on Trump’s impeachment trial.

In that time, additional Republicans have indicated they’ll back the resolution, including Sen. Jerry Moran (R-Kan.). Sens. Lamar Alexander (R-Tenn.), Bill Cassidy (R-La.) and Lisa Murkowski (R-Alaska) also voted to advance the legislation on Wednesday; it is not yet clear if all three will back the resolution on its final vote.

Even with their support, however, the legislation will still lack the votes to overcome a near-guaranteed veto.

Just before Wednesday’s procedural vote, Trump tweeted that “it is very important for our Country’s SECURITY that the United States Senate not vote for the Iran War Powers Resolution,” arguing that such a vote would “show weakness.”

“If my hands were tied, Iran would have a field day,” Trump continued. “Sends a very bad signal. The Democrats are only doing this as an attempt to embarrass the Republican Party. Don’t let it happen!”

Leading Republicans voiced their support for Trump’s position, arguing that Kaine’s measure “is too blunt and too broad,” as Senate Majority Leader Mitch McConnell (R-Ky.) said on the Senate floor Wednesday.

“Our colleagues couldn’t even acknowledge the president’s decisive action,” Sen. John Cornyn (R-Tex.) said on the floor, arguing that Trump had no obligation to consult Congress before the Soleimani strike. “This was clearly not only within the president’s constitutional authority, but it falls within his duty to prevent and stop threats against the United States.”

But Republicans backing the resolution openly rejected the argument that their support meant rejecting a tough approach to Iran that includes military options.

“This is neither hawkish nor dovish,” Lee argued to reporters. “It focuses it instead on the fact that moving forward, any action that we take involving Iran … needs to be authorized by Congress.”

The House, which passed a nonbinding war powers resolution last month, will probably have to take up the Senate’s version before it is sent to Trump’s desk.

Yet it is clear that proponents of the legislation are hoping it does work to prevent Trump from further ratcheting up tensions, even if he continues to tweet against and veto the resolution.

“Our feeling,” Kaine said, “is when Congress stands up and acts … even if he chooses to veto it and we can’t override, the will of both bodies and the public that they represent, that is something that could well be a factor in his decision-making.”