WASHINGTON — A key group of Senate Democrats urged Minority Leader Mitch McConnell Monday morning to exercise his authority as head of the Senate GOP and «prevail» to end Sen. Tommy Tuberville’s «reckless control» of military nominations.

“We are writing to you today to share our deep concern for the stability of our Armed Services and national security and ask you to exercise your leadership to protect the readiness of our military,” the senators wrote in a letter to McConnell, according to a copy obtained by NBC News.

Tuberville, a Republican from Alabama, has been «single-handedly blocking the promotion of hundreds of generals and admirals» and «threatening our national security» over his opposition to a Defense Department policy that pays for the travel expenses of service members who need to leave the state to obtain an abortion, the letter said.

“We know that you share our concerns about the consequences of this suspension on our Armed Services, and as the leader of your conference, we urge you to take stronger action to resolve this situation,” the senators said in their letter to McConnell.

Democratic signatories to the letter, led by Sen. Mazie Hirono of Hawaii, include Sens. Elizabeth Warren of Massachusetts, Jacky Rosen of Nevada, Richard Blumenthal of Connecticut, Tim Kaine of Virginia, Mark Kelly of Arizona and Tammy Duckworth of Illinois, along with Sen. Angus King of Maine, an independent who runs with Democrats.

They all serve on the Senate Armed Services Committee with Tuberville, who has said he would end his block on military nominations, which now affects more than 250 officers, if the Pentagon’s abortion policy is voted on.

A McConnell spokesman had no comment when asked about the letter from Senate Democrats.

Senate Majority Leader Chuck Schumer last week signaled his willingness to give Tuberville an independent vote to affirm the policy, but entrusted Senate Republicans with the responsibility of finding a way forward.

Senator Tommy Tuberville speaks at a press conference at the Capitol on June 14.File Kevin Dietsch/Getty Images

“If you want to have a yes vote, we won’t object,” Schumer said Wednesday at a news conference in response to a question from NBC News. “Tuberville said he wanted a vote, we’ll see what happens. The bottom line is that it depends on Republican leadership.

“This is a problem that they have in their bench, that they have with the country. They are putting our security at risk and it is up to them to fix it,” Schumer said.

In the past, McConnell has criticized controlling Tuberville as «not the best way to do it» when dictating a policy change. But last week he told reporters that he would be «reluctant» to try to disrupt the Tuberville blockade by changing the Senate retention process.

“We have retentions on both sides. What usually happens is you figure it out, and I think that’s where we should stay,» McConnell said.

Several Democrats on the committee see it differently. They wrote in their letter to McConnell: “As leader of the Republican Conference, we are counting on you to hold your colleagues accountable when they recklessly cross the lines and upset the Senate order.

“Senator Tuberville’s continuation of this impasse is reckless, dangerous, and must end. It is up to you to act now, for the safety of our nation.»

julie tsirkin and kate santaliz contributed.