As the Obama administration scrambles for options in Syria, officials lament that the United States has no leverage over the Assad regime, Russia or Iran to persuade them to halt their ongoing atrocities, especially in Aleppo. But behind the scenes, the White House is actually working to weaken a sanctions bill lawmakers in both parties see as providing leverage against all three.

According to lawmakers and staffers in both parties, the White House is secretly trying to water down the Caesar Syria Civilian Protection Act, a bipartisan bill that would sanction the Assad regime for mass torture, mass murder, war crimes and crimes against humanity. The bill, guided by House Foreign Affairs Committee ranking Democrat Eliot Engel (N.Y.), would also sanction entities that aid the Syrian government in these atrocities; that includes Russia and Iran.

The bill, named after a Syrian defector who presented the world with 55,000 pictures documenting Assad’s mass torture and murder of more than 11,000 civilians in custody, has 70 co-sponsors, a majority of whom are Democrats.

The House was set to pass the bill late last month, but the White House made an 11th-hour plea to lawmakers to delay. The White House said the vote would upset the then-active cease-fire agreement with Moscow, and Democrats pulled their support, said Rep. Adam Kinzinger (R-Ill.), one of the original sponsors of the bill.

Now the White House has told members and staffers that the bill’s sanctions on Iran could violate the nuclear agreement the Obama administration struck with Tehran last year and the Russia sanctions could hurt any future efforts to work with Moscow diplomatically on Syria.

“There’s this delusional idea that you can have peace in Syria without an ‘or else.’ This is potentially that ‘or else,'” Kinzinger said. “Anybody associated with helping the regime, you could hold this up and say, ‘This could be a sanctions leverage unless there’s a cease-fire.'”

A spokesman for Engel declined to comment on the ongoing negotiations between the White House and Engel over the sanctions bill. But in a statement, Engel emphasized the importance of the bill’s sanctions on countries that help Syrian dictator Bashar al-Assad commit atrocities.

“I’ve been negotiating with the administration on my bill, and I’ll keep working to resolve differences,” Engel said. “For me, it’s this simple: we need more tools to crack down on the Assad regime and any person or government helping sustain Assad’s campaign of violence.”

Two Syrian activists who met with the staff of House Democratic Leader Nancy Pelosi (Calif.) told me that a Pelosi staffer told them there was little to no chance the bill would be voted on this year. A House Democratic leadership aide disputed the activists’ characterization of the meeting and said that Pelosi had never officially agreed to move the bill under a suspension of the rules.

House Speaker Paul D. Ryan (R-Wis.) and House Majority Leader Kevin McCarthy (R-Calif.) are supporters of the bill. Ryan accused the White House of turning a blind eye to war crimes in Syria in his weekly briefing Sept. 22.

“At no point has the Assad regime stopped committing atrocities against the Syrian people,” Ryan said. “That is why it is so troubling to me that the White House is blocking bipartisan legislation to impose new sanctions against the Assad regime.”

Noting that the original excuse for a delay — the cease-fire — had collapsed, Ryan called on the White House to allow Democrats to support a vote on the bill.

“So what’s the excuse now? This is not a game. I think the administration is essentially protecting some of the world’s worst war criminals,” he said.

Democratic aides point out that Ryan and McCarthy have the power to bring the Syria sanctions bill to the floor without Democratic agreement. That path would require regular order, which means a floor debate and a voting procedure that demands extra floor time. Also, that would put Republicans in the awkward position of bringing up a Democrat-led bill that doesn’t have Democratic leadership support.

Kinzinger said that Republicans are waiting to see what the administration’s negotiations with Engel produce, but he warned that Republicans would not support the bill if the White House fundamentally weakens it.

“I’m willing to come to whatever agreement’s necessary that is actually effective, but if there is an attempt to make this toothless, they are going to have a hard time getting it through,” he said.

The version of the bill that was approved on a bilateral basis by the House Foreign Affairs Committee in July would impose new sanctions on the Assad regime and its supporters, spur investigations meant to fuel the prosecution of war crimes in Syria, and encourage a process to find a negotiated solution to the crisis. Specifically, it would require the president to impose new sanctions on any entity that does business with or finances the Syrian government or its military or intelligence services, which includes Russia and Iran. It would also require sanctions on any entity that does business with several Syrian government-controlled industries, including the airline, telecommunications and energy sectors.

Stephen Rapp, who until recently served as the State Department’s ambassador at large for war crimes issues, said the United States should let the Assad regime, Russia and Iran know that there will be some accountability for the war crimes they are committing in Syria.

“It’s important to send the signal that those who engage in war crimes and those who aid and abet them are held to account with tools that are effective, and in the short term the most effective is sanctions,” he said. “The White House should not be opposing the legislation. Congress is doing the right thing. It’s a bipartisan bill.”

White House Press Secretary Josh Earnest said last week: “The concern we have with the current congressional proposal that’s being debated is that it would deploy those sanctions essentially unilaterally.” A spokesman for the National Security Council declined to comment on the White House’s negotiations over the legislation.

When it came to Iran, the Obama administration opposed sanctions but Congress insisted on them and passed them over President Obama’s objections. Other allied nations followed suit, and those sanctions contributed to the pressure that eventually brought Iran to the negotiating table. Later, the Obama administration took credit for the sanctions regime when announcing the Iran nuclear deal.

For the Syria sanctions, the Obama administration should let the legislative process play out and take the leverage lawmakers are offering. In the best-case scenario, Obama can negotiate from a position of greater strength. At the very least, one branch of the U.S. government will have acted to try to end the mass atrocities being inflicted on Syrian civilians.