A bipartisan group of lawmakers in the U.S. Congress introduced legislation Thursday to lift President Trump’s ban on transgender military service.

The legislation, filed in both the U.S. House of Representatives and U.S. Senate, would express a congressional opinion “that anyone who is qualified and can meet the standards to serve in the military should be eligible to serve,” according to a press release. It would also forbid each branch of the armed services from involuntarily discharging trans service members, or denying their reenlistment or continuation of service. The military would be unable to deny a person from enlisting or becoming an officer on the basis of their gender identity.

“President Trump’s ban on transgender service members is discrimination, it undermines our military readiness, and it is an insult to the brave and patriotic transgender Americans who choose to serve in our military,” said Sen. Kirsten Gillibrand (D-NY), ranking member of the Senate Armed Services Committee’s Subcommittee on Personnel and lead sponsor of the bill, in a statement. “The heads of the Army, Navy, Air Force, Marine Corps, and Coast Guard have all testified to Congress that transgender service members are serving in our military without any problems. We should end this discriminatory ban for good and ensure our transgender service members can continue to do their jobs, serve with dignity, and protect our country.”

The president tweeted in July 2017 that he would order the military to ban transgender people from serving. The administration issued a presidential memorandum on it the following month, setting off a wave of lawsuits resulting in injunctions against the ban. In March 2018, the administration released new memorandums detailing how and why it would implement the ban. The policy was reportedly written at the behest of Vice President Mike Pence by anti-LGBTQ activists at the Heritage Foundation and the Family Research Council. The U.S. Supreme Court voted along ideological lines to lift the injunctions that had put the policy on hold while the cases work themselves through the court system, and the ban will go into effect after an additional injunction is lifted.

Sen. Susan Collins (R-ME) was the only GOP senator to sign on as an original sponsor of the bill. In July 2017, she was also the only GOP senator to sign a letter to James Mattis, secretary of defense at the time, urging the Department of Defense not to institute the president’s trans service ban.

“As one of the leaders in the successful effort to repeal the military’s discriminatory ‘Don’t Ask, Don’t Tell’ policy, I strongly believe that anyone who is qualified, able to be deployed into war zones, and wants to serve should continue to be allowed to do so, including our transgender troops,” said Sen. Collins in a statement. “If individuals are willing to put on the uniform of our country and risk their lives for our freedoms, then we should be expressing our gratitude to them, not trying to kick them out of the military.”

Gillibrand and Collins teamed up with the late Sen. John McCain (R-AZ) in September 2017 to introduce a previous version of the bill. It’s unclear if any other GOP senators will support the current legislation.

Though the administration claimed in its memorandum that the president, as commander-in-chief, has the constitutional authority to institute the ban, the Constitution tasks Congress with maintaining the military.

According to some constitutional law experts, the division of power regarding who has authority to place restrictions on military service eligibility hasn’t been settled by the judicial branch. “If you look, there’s a lot of historical precedent for Congress to legislate on these matters,” said constitutional litigator Gregory Lipper in an interview with Rewire.News. “You may remember when Bill Clinton was elected, he campaigned on allowing gays and lesbians to serve openly in the military, and then it ended up being the ‘Don’t Ask, Don’t Tell’ compromise. So that was a legislative compromise and it ended up being repealed legislatively …. One way or another, ‘Don’t Ask, Don’t Tell’ was created by Congress and repealed by Congress.”

Lipper also cited an instance in the 1990s when Congress lifted some restrictions on women serving on combat ships. The key difference between those bills and the trans military ban, he said, is that Congress and the president were in agreement on the legislative solutions. “You didn’t necessarily have a clash, so these questions never got teed up,” said Lipper. Regardless of the constitutional issues, the first step is getting the legislation passed.

Passing the bill is itself a tall order, according to LGBTQ advocates working on the issue. Senate Majority Leader Mitch McConnell (R-KY) is unlikely to allow a floor vote on stand-alone legislation, but it could be added as an amendment to the military authorization bill. “Just because it’s been introduced as a bill doesn’t mean that anybody actually expects it to pass as a solid, whole bill alone,” said Mara Keisling, executive director of the National Center for Transgender Equality, in an interview with Rewire.News. “It would be great in my opinion if this got attached as an amendment to [the National Defense Authorization Act (NDAA)], and the other beauty of that is it would only have to be attached in one of the chambers.”

Attaching an amendment lifting the trans military ban to the NDAA could be an easier path to success for Gillibrand’s legislation, according to Keisling. If, for example, the House attached the amendment to their version of the NDAA, and the Senate didn’t, the bill would be finalized in conference committee between the two chambers to produce a final version for each to vote on. If Democrats hold firm, they could force Senate Republicans to vote against authorizing the military in order to block the amendment. Should the final bill then clear the Senate with the amendment, President Trump could be painted into a politically impossible corner.

“The president would be forced to either sign it or shut down the military,” said Keisling.

According to Lipper, however, the president could just attach a signing statement saying he won’t follow the statute, in which case the ban would head back to the courts once again, raising serious constitutional questions. “Ultimately if there’s a fight about it, it’ll go up to the Supreme Court and all bets are off with this Supreme Court.”