A leading liberal Senate Democrat is drafting a measure that would sharply constrain White House power to wage military action abroad as senators prepare for a full-fledged debate over war authorization.

Sen. Jeff Merkley (D-Ore.) wants to present a more restrictive alternative to legislation — written by Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) and Sen. Tim Kaine (D-Va.) — that envisions handing much of the war-making powers back to Congress after years of ceding it to the executive branch.

Writing a new authorization of the use of military force on Capitol Hill has, for several years, been a quixotic effort limited to the likes of Kaine and opposed by congressional leadership. Meanwhile, three presidential administrations have operated under a pair of measures known as Authorization for Use of Military Force — or AUMFs — passed after the Sept. 11, 2001 attacks. Critics, however, say the AUMFs have been stretched to rationalize military actions that have never been specifically sanctioned by Congress.

“It’s too big of an issue in terms of the lives of our citizens and our treasury to leave that to one person,” Merkley said in an interview. “It should be difficult to decide to go to war. And that means that Congress needs to act.”

Merkley’s proposal, detailed to The Washington Post in advance of its release, has several key differences from the Corker-Kaine measure unveiled last month that helped break a deadlock in the debate over war powers on Capitol Hill.

One is that Merkley explicitly writes in a three-year time limit, or a “sunset,” until the war authorization expires and lawmakers are forced to revisit the issue. Republicans have opposed the idea of a sunset, and the Corker-Kaine measure aims to strike a balance by requiring the administration to submit a new war plan every four years, although the current war powers would stay intact if Congress didn’t act.

Merkley’s legislation only authorizes military action against al-Qaeda, the Taliban and the Islamic State, and in two countries: Afghanistan and Iraq. The Corker-Kaine legislation also authorizes use of force against “associated forces” that include al-Qaeda in the Arabian Peninsula; al-Shabab, a militant faction in East Africa; al-Qaeda in Syria; the Pakistan-based Haqqani Network, and al-Qaeda in the Islamic Mahgreb in North Africa. It allows for U.S. military operations in four additional countries: Somalia, Yemen, Libya and Syria.

Merkley, who joined the Senate Foreign Relations Committee last year, emphasized that his legislation is meant to green-light military action against just the terrorist organizations targeted by the 2001 and 2002 war authorizations.

But “all the other actions, the president needs to come and ask Congress to open the door,” the second-term senator added.

That also includes the use of ground troops. Under Merkley’s bill, the president would be required to alert Congress within 48 hours of introducing ground troops, who would be allowed to remain only if lawmakers’ approval.

Several committee members in both parties have lined up behind Corker and Kaine’s measure, including Sens. Christopher A. Coons (D-Del.), Jeff Flake (R-Ariz.) and Todd C. Young (R-Ind.). Even so, Kaine, who has tried for years to force Congress to reassert its role in authorizing military action, is bracing for the opposition.

During a committee meeting last month when senators discussed the broad contours of Corker and Kaine’s proposal, at least three members expressed “significant discomfort with the basic framework” of the AUMF, Merkley said. At least one was a Republican.

“The White House generally thinks it’s too restrictive, and the left … thinks it’s not restrictive enough,” Kaine said. “It imposes significantly more constraint on the ongoing effort against nonstate terrorist groups than the current status quo, but people have to decide whether that’s enough for them.”

The Senate Foreign Relations Committee is scheduled to hear testimony from experts later Wednesday on Corker and Kaine’s war authorization measure, and senators are certain to question Secretary of State Mike Pompeo on the issue when he appears before the panel next week. The actual markup of the AUMF in the committee won’t occur until after the Memorial Day recess, aides say.