Sen. Kirsten Gillibrand (D-NY) is working on legislation to block President Trump’s proposed ban on transgender people serving in the military, part of an effort to move fellow lawmakers from bashing the controversial White House announcement to actually trying to find concrete ways of reversing it.

“Our office is working on legislation to stop this from happening and on an amendment to the NDAA, but these are all long-term fixes,” Moran Banai, a senior adviser in the senator’s office, said in an email, referencing the large defense budget bill known as the National Defense Authorization Act. The email was obtained by Vox.

In the short term, Gillibrand is trying to get other senators to sign on to a letter asking Defense Secretary James Mattis to “advise the President against” choosing to put a trans military ban in place.

It also calls on Mattis not to kick any trans service member out of the armed forces until the Pentagon completes an ongoing internal assessment of what allowing transgender individuals to enlist in the armed services would do to the military’s readiness to fight and lethality when in the fight.

“Forcing these brave Americans out of our military would be cruel and discriminatory. It would harm our readiness by denying the military of these service members’ capabilities and requiring the military to replace them at a time when the recruiting pool for the services continues to shrink,” the draft reads.

Sen. Cory Booker (D-NJ) is also working on legislation to block the ban, the Washington Post reports. Yesterday, Booker told me there were “lots of discussions” happening among his colleagues about how to do it.

And Democrats aren’t alone in their opposition. Many Republicans in Congress, including Sens. John McCain and Orrin Hatch, are opposed to the ban. “There should be no discrimination,” Hatch told me today.

McCain, for his part, has said “any American who meets current medical and readiness standards should be allowed to continue serving.” Despite his opposition, it’s still unclear if McCain, who chairs the Armed Services Committee, will allow for an amendment that aims to block a ban on trans service members to get into the NDAA.

For now, Trump’s tweets are the administration’s only actual move to ban transgender troops. In a message to top military officers, Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff, said the current policy — which allows trans troops to serve openly — won’t change unless and until the Pentagon gets actual orders from Trump.

“There will be no modifications to the current policy until the president's direction has been received by the Secretary of Defense and the Secretary has issued,” he wrote.

Gillibrand and her allies aren’t waiting for those orders to come.