Sen. John McCain, R-Ariz., has signed on to a new bill to be introduced Friday by Sens. Kirsten Gillibrand, D-N.Y., and Susan Collins, R-Maine, to block President Trump's order to ban transgender military service.

The stand-alone bill, which is also co-sponsored by Sen. Jack Reed, D-R.I., the top Armed Services Democrat, has the same language as an amendment proposed by Gillibrand and Collins this week for the National Defense Authorization Act that would prohibit the military from barring service based on gender. That amendment never received a floor vote due to a dispute between Republicans and Democrats over debate of the NDAA.

"Any member of the military who meets the medical and readiness standards should be allowed to serve — including those who are transgender," McCain said in a statement.

Gillibrand, D-N.Y., who is the ranking member of the Armed Services military personnel subcomittee, said she and Collins have not given up the effort to block Trump from instituting his new policy.

"Thousands of brave transgender Americans love our country enough to risk their lives for it, fight for it, and even die for it, and Congress should honor them and let them serve," she said. "Doing otherwise would only harm our readiness at a time when our military is deployed around the world in defense of our country."

Last month, Trump ordered the military to phase out gender reassignment surgeries by March, abandon plans to begin recruiting transgender troops, and decide how to handle those already serving.

The White House said the intent of Trump's presidential memorandum is to roll back the Obama administration decision to allow open transgender service beginning last summer.

Defense Secretary Jim Mattis said he is setting up a panel of experts to decide how to execute the president's order.

The order also triggered a series of federal lawsuits in D.C., Maryland, California, and Washington state against Trump and Mattis because of the policy.

The nine transgender plaintiffs in the Washington lawsuit filed a motion for an injunction Thursday, asking the federal district court to block Mattis from implementing any ban while the case is being heard. Plaintiffs who sued in D.C. have also asked for an injunction and the Trump administration has a deadline to respond next week.

The Senate bill also puts pressure on Trump from Capitol Hill, though it could face a tough road in the House.

"Today's stand-alone bill gives Congress another chance to protect the military's proud record in which service members, once welcomed and deemed fit to serve, are not cast aside for political reasons," said Aaron Belkin, director of the Palm Center, an advocacy group for transgender military service.