The effort to protect transgender troops already serving in the military just got a major boost.

The top two members of the Senate Armed Services Committee, Sens. John McCain (R-AZ) and Jack Reed (D-RI), introduced legislation with Sens. Kirsten Gillibrand (D-NY) and Susan Collins (R-ME) on Friday to stop the Defense Department from following through on President Donald Trump’s directive to kick out trans service members.

This comes four days after Gillibrand and Collins introduced an amendment to the Pentagon budget bill that aimed to block the ban. But senators chose to move forward with the budget bill without voting on the transgender military ban provision — which meant a new effort was needed.

That’s what this new effort is — and it could be more successful because McCain supports it as a co-sponsor. As a top senator and leader on military affairs, his priorities carry weight. It would be odd for other senators to oppose him on a military-related piece of legislation. However, if passed, the bill might be stopped in the more conservative House of Representatives.

“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 press release about the new legislation. “Despite being denied a vote on my bipartisan amendment to defend our transgender service members, we are not giving up in this fight,” Gillibrand said in the same press release.

On July 28, 45 senators sent a letter to Defense Secretary Jim Mattis requesting that he tell Trump the ban is a bad idea. It’s expected that at least those 45 legislators will support the new effort.

In addition to stopping the military from kicking out transgender service members solely because of their gender identity, the new legislation would also require Mattis to assess the effects enlisting transgender people would have on the military, and he would have to send the review’s results to Congress by the end of the year.

Trump gave Mattis until February 21, 2018, to complete that review, but this new legislation give moves up the timeline by two months.

Transgender troops have been allowed to serve openly in the military since former Secretary of Defense Ash Carter announced they could do so in June 2016. There are an estimated 1,320 to 6,630 active-duty trans troops, according to a 2016 RAND study.