New Jersey is joining 14 other states and the District of Columbia in an effort to overturn President Donald Trump's proposed ban on transgender military service members, officials announced Tuesday.

State Attorney General Gurbir Grewal said Tuesday his office had filed papers to join an ongoing lawsuit challenging the constitutionality of the Trump administration's policy, which is currently on hold pending several legal challenges.

The president last year announced he would take steps to bar transgender people from serving in the military "in any capacity," citing "tremendous medical costs and disruption."

The move drew sharp criticism from LGBT and civil liberties advocates, as well as members of the president's own party, though the Republican National Committee voted last month to support the plan.

New Jersey's legal filing joins attorneys general across the country in an amicus brief supporting an August lawsuit filed by transgender service members seeking to block the ban.

Grewal said in a statement that the ban "doesn't just demean our armed forces," but also violates the constitution.

"As our amicus brief makes plain, we believe that the full participation of transgender persons strengthens both our military and our nation," he said.

The suit, known as Ryan Karnoski v. Trump, is being heard in federal court in Washington state.

New Jersey joins lead state Massachusetts as well as California, Connecticut, Delaware, Hawaii, Illinois, Iowa, Maryland, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Vermont and Washington, D.C. in the friend-of-the-court brief.

The move marks the latest in a series of efforts by Gov. Phil Murphy's administration to take on the Trump administration through the Attorney General's Office, which largely shied away from political fights with Trump during former Gov. Chris Christie's tenure.

In the last week, Grewal's office signed on to a multi-state lawsuit against the Federal Communications Commission's rollback of net neutrality rules and a letter opposing the federal government's expansion of offshore drilling.

S.P. Sullivan may be reached at ssullivan@njadvancemedia.com. Follow him on Twitter. Find NJ.com on Facebook.