Senators on Monday unveiled their long-awaited legislation to update and restrict the president’s war-making powers just days after the Trump administration launched a military offensive against the Bashar al-Assad regime.

But under the new proposal, lawmakers refused to grant President Donald Trump that explicit authority because, they argue, the president is sending mixed messages and hasn’t outlined a clear long-term strategy with regard to the Syrian civil war.

“There’s going to be a lot of misgivings about giving any kind of broader authorization to the executive if we don’t know where we’re heading in Syria—one day we’re putting more troops in, another day we’re taking them out. That’s not a strategy at all,” Sen. Chris Murphy (D-CT) told The Daily Beast.

Friday’s coordinated airstrikes on the Syrian dictator’s chemical weapons infrastructure, in response to the regime’s alleged chemical attack earlier this month against innocent civilians in Douma, renewed calls among lawmakers for Congress to take back their constitutional obligation.

But absent a longer term strategy in Syria, frustrated lawmakers were hesitant to grant Trump the specific authority to conduct military operations against Assad’s forces, apart from ongoing coalition efforts against ISIS in the country. In other words, using military force against the Assad regime would remain illegal.

“If [Trump] wants to do something that’s going to be an ongoing effort, then I know he has to come to Congress for an authorization,” Sen. Bob Corker (R-TN), the chairman of the Senate Foreign Relations Committee, told The Daily Beast, adding that he “said exactly that” to the president the day before U.S., French and British forces targeted the Assad regime directly.

Crafting a new authorization for the use of military force (AUMF) is a rare move for a Congress that has, in recent years, been reticent to reassert its constitutional authority over U.S. foreign policy—namely, its Article I power to declare war. The Bush, Obama and Trump administrations have relied on outdated war authorizations from 2001 and 2002 to legally justify U.S. military operations around the world, often targeting terror groups that did not even exist at the time those authorizations were crafted ahead of the wars in Afghanistan and Iraq.

The new authorization, crafted by Corker and Sen. Tim Kaine (D-VA), “gives [the administration] the flexibility to be successful that they now have, but it also keeps Congress in the loop and having the ability to stop it if they think it’s egregious,” said Corker.

More specifically, the authorization allows the president to use military force against terror groups including al Qaeda, the Taliban and ISIS, in addition to offshoots of those groups identified in the legislation as “designated associated forces.” It would not, however, allow the president to use military force against a nation state. In other words, the new authorization still would not provide a legal justification for Trump’s decision to launch coordinated airstrikes last week on Syrian dictator Bashar al-Assad’s chemical weapons infrastructure.

The administration, critics contend, has sent mixed messages about its intentions in the aftermath of the alleged chemical weapons attack. While Trump himself mentioned a “sustained” campaign against the regime during his address to the nation on Friday night, Defense Secretary James Mattis called the strikes a “one-time shot” aimed at deterring future chemical attacks on the part of the Assad regime. And just days before the alleged chemical attack took place, Trump’s top national-security officials were forced to re-affirm the U.S.’s commitment to eradicating ISIS and other terror groups in Syria, after the president publicly suggested that the U.S. should pull out of Syria. Lawmakers sought to highlight those discrepancies as they push for a substantive voice on the president’s war-making powers.

“Assad needs to face consequences for his war crimes, and I would be open to supporting military action if the president came to us for approval and laid out a Syria strategy. But he doesn’t have the authority to do it on his own and striking without a broader strategy is reckless,” Kaine, a co-author of the new AUMF, told The Daily Beast. “If we're going to order our troops to risk their lives, then there has to be a debate and vote by Congress to say this is in the national interest.”

Lawmakers have called on the Trump administration to develop a longer term strategy for Syria, even if Friday’s strikes amounted to simply a one-off offensive in response to the alleged chemical weapons attack. Most Republicans, including Corker, and some Democrats have argued that the nature of the strikes is consistent with the president’s Article II constitutional authority.

Even if the updated authorization can clear the foreign relations committee after an open-amendment process, senators don’t yet have a guarantee from Senate Majority Leader Mitch McConnell (R-KY) to hold a full floor vote on the legislation. Complicating matters further, House and Senate leaders would be hard-pressed to force tough votes for their members in an election year.

“My first goal is to move something out of the committee, so I don’t really worry about much beyond having a successful vote in the committee, which has been difficult for years,” Corker said. “It is a political season, and everybody says they want to weigh in on AUMF—we’ll see if everybody really wants to weigh in on an AUMF. Until we did something here, I can’t imagine [the House] wanting to take it up.”

The issue has been a thorny one on Capitol Hill for years, with some Democrats even challenging the Obama administration over its refusal to entertain a new war authorization. Under Trump, though, the issue has gained more attention and steam as lawmakers from both parties question the president’s foreign-policy prowess.

“There’s a lot more interest in this now because of what’s going on in Syria, and with troops losing their lives in Niger—people were saying, we have troops there? There are things that are pushing us toward finally acting on this. It’s just been far too long,” Sen. Jeff Flake (R-AZ), a member of the foreign relations committee who has co-authored previous AUMFs with Kaine, said in an interview.

Last summer, the House Appropriations Committee voted to scrap the 2001 AUMF; but that amendment never made it to the House floor. In September, the Senate rejected Sen. Rand Paul’s (R-KY) amendment that would have repealed both the 2001 and 2002 authorizations and would have given Congress six months to craft a new one.