As the prospect of a confrontation with Iran continues to rise, an increasing number of members of Congress have a new objective: ensuring President Trump does not launch a war without their approval.

The concern has brought together two lawmakers from opposite sides of the aisle. On Tuesday, Republican Rep. Matt Gaetz and Democratic Rep. Ro Khanna will unveil an amendment to the National Defense Authorization Act to codify congressional authorization for any military action against Iran.

According to a draft of the amendment obtained by TIME, Trump would be required to seek approval from Congress before authorizing war on Iran — or risk losing funding for the venture entirely. The amendment explicitly states that, with the exception of the War Powers resolution which requires Congressional approval anyway, “no federal funds may be used for any use of military force in or against Iran unless Congress has declared war.”

Authorization for the Use of Military Force — legislation Congress passed after the Sept. 11 attacks that broadly handed the President power to fight al-Qaeda and “affiliates” in various countries around the globe — does not apply to Iran.

Khanna said in an interview with TIME that Article I of the Constitution explicitly lays out Congress’ right to declare war, and he is just trying affirm that responsibility.

“We get to decide to go to war,” Khanna said in an interview. “We think the framers set that up because we knew that the executive [branch] would otherwise get us into wars that were not supported by the public.”

In addition to Gaetz and Khanna, the amendment currently has five co-sponsors: Jim Himes, Alexandria Ocasio-Cortez, Barbara Lee, Deb Haaland and Anthony Brown. More are expected to join before the amendment is officially unveiled.

“The White House is trying to goad us into a military conflict that is completely irresponsible. Diplomacy is what grants us peace and stability — not war,” Ocasio-Cortez said in a statement. “We will not let powerful people outside of Congress force our country into war. I proudly support this amendment prohibiting the use of any funds for a war with Iran without Congressional authorization.”

Khanna and Gaetz’s decision to introduce the amendment coincides with an escalation of tensions between the U.S. and Iran. For the past several weeks, Trump has increased the number of troops, ships and aircraft in the Middle East to deter Iran. This came to a head last week when the Iranian military shot down an American drone. The President said he initially authorized retaliatory military strike against Iran, but pulled back amidst skepticism and estimations it would kill 150 people. On Monday, Trump signed an executive order imposing sanctions on the Iranian Supreme Leader, Ayatollah Ali Khamenei, along with eight Iranian military officials, including one the administration claimed was responsible for the drone attack.

Khanna had tried to introduce a similar amendment in the House Armed Services committee but aides said he withdrew that to heighten its visibility and ensure some version made it into the final spending bill. However, he said Monday that Trump’s acknowledgement that he approved the missile strike amplified the urgency to push this type of Congressional action. “This is on everyone’s mind,” he said.

Gaetz, an ally of Trump’s who said he has spoken with the President frequently about Iran, had a different perspective. He trusts the President’s instincts, he explained, but is wary of some of his advisers like National Security Adviser John Bolton and Secretary of State Mike Pompeo.

“If anything the [legislation] is a symbol to some of the war hawks within the Trump Administration that we don’t want to be in forever wars in the absence of robust debate and approval by the Congress,” he said in an interview.

But the amendment faces an uphill battle to become law, both procedurally and politically. It still needs to be considered by the Rules Committee before it can officially come to the floor for a vote. If the Rules Committee approves it and it proceeds to the floor, the House would likely not vote on it until after the July 4 recess, when the House is expected to vote on the NDAA.

Then, there are the political considerations. Gaetz is the sole Republican to currently support it, despite interest from some of his colleagues. While a lack of Republican support won’t necessarily matter in the House, given that Democrats control the majority, the reticence on this issue could matter in the Senate, where Republicans are in control. A group of bipartisan senators have introduced their own amendment to the NDAA affirming congressional power for military authorization with Iran. But it remains to be seen if Republican leadership will allow even a vote on that when the Senate votes this week.

Despite the uncertainty surrounding the amendment, Gaetz, noting the unique amalgamation of the sponsors — he is among the more conservative members of their caucus, while Ocasio-Cortez and Lee are among the more progressive Democrats — predicted that anti-war sentiments would continue to gain traction.

“We are starting to see a new anti interventionist regime change war coalition forming in the Congress and in the country among right-wing populists and left-wing populists,” he said.

Write to Alana Abramson at Alana.Abramson@time.com.