LGBT activists are calling on the U.S. Senate to reject President Donald Trump's nominee to become secretary of the Army.

On Friday, the White House announced that Trump had picked Tennessee state Senator Mark Green for the post.

A former Army officer and West Point graduate, Green is popular among conservative Republicans.

LGBT activists say that putting Green, a 52-year-old physician, in charge of the Army would be “unconscionable” given his opposition to LGBT rights.

“Mark Green is a danger to every LGBTQ soldier bravely serving our country,” said Chad Griffin, president of the Human Rights Campaign (HRC). “Mark Green has called for states to refuse to issue marriage licenses to same-sex couples and appallingly said that being transgender is a ‘disease.’ He has used his office in Tennessee to push ‘license to discriminate’ legislation and undermine the basic civil rights of LGBTQ people at every turn. It would be unconscionable to put this man in charge of our Army. We call on every U.S. Senator to stand up for LGBTQ service members and reject this nomination.”

Stephen Peters, national press secretary for the Human Rights Campaign (HRC), added: “As a Marine discharged under ‘Don’t Ask, Don’t Tell,’ I am appalled that Donald Trump would seek to put this man in charge of the U.S. Army. Under President Obama’s leadership, we finally ended policies that forced service members, their partners, and families to hide who they are and treated them as second class citizens. There are thousands upon thousands of us who fought this injustice so that we could serve openly today – and who are now threatened by the appointment of a man who has spent his career working to undermine our rights.”

If confirmed by the Senate, Green would succeed Eric Fanning, who made history during the Obama-era as the first openly gay person to head the Army.