President Trump’s nominee to be the Navy’s general counsel, who has languished in the Senate for more than 14 months, is being held up by Sen. Kirsten Gillibrand, D-N.Y., her office confirmed Thursday.

The senator did not immediately provide a reason for her hold on Charles “Cully” Stimson. But the senior legal fellow at the Heritage Foundation was a strong critic of Gillibrand’s attempts in recent years to pass legislation reforming military sexual assault prosecutions.

In 2016, Gillibrand’s Military Justice Improvement Act, a signature piece of legislation for the senator, was facing a third potential vote in the chamber after failing twice before. The bill would have removed sex assault prosecutions from the military chain of command.

Stimson wrote a critical column dubbing the legislation the “Military Justice Destruction Act.”

The senator was “pushing her radical scheme that, if enacted, would render the military justice system unworkable and ineffective,” he wrote in June 2016 for the conservative think tank’s Daily Signal, just days before the Senate declined to vote on Gillibrand’s bill.

A similar 2015 blog by Stimson argued Gillibrand’s bill could hurt victims amid the senator’s earlier attempts at passage. Stimson authored a 2013 Heritage policy paper that laid out an argument against removing commanders from decisions on prosecuting assaults.

Stimson declined a request to comment for this report.

His nomination has remained frozen in the Senate since July 2017 despite a direct plea to Majority Leader Mitch McConnell from Defense Secretary Jim Mattis, and a letter urging confirmation from three former Navy secretaries.

“Nearly 16 months into this administration, many of the Senate-confirmed leadership positions on my staff remain vacant,” Mattis wrote to McConnell in a June letter obtained by the Washington Examiner.

At the time, the defense secretary listed Stimson as the third most important Pentagon nominee to confirm. The other two higher nominees were Paul Ney, the Pentagon general counsel who was confirmed in July, and Tony Kurta, who withdrew his nomination as head of personnel and readiness late last month after his nomination had languished since November 2017.

Former Navy Secretaries Gordon England, Donald Winter, and J. William Middendorf wrote to McConnell last month urging the leader to bring Stimson up for a vote as soon as possible.

“The Department of the Navy has immense challenges. We know, as former Navy secretaries, that having a sage, experienced, Senate-confirmed general counsel is invaluable in leading the department. And we are confident that Mr. Stimson is the right man for the job,” the wrote.

The Senate Armed Services Committee, of which Gillibrand is a member, advanced Stimson’s nomination favorably on July 20, 2017, following a public hearing. Since then, the nomination has been waiting for a vote on the Senate floor. Any senator is able to hold up a nominee, almost always anonymously, if they wish.

Gillibrand’s hold comes as the battle over confirmations is heating up.

Secretary of State Mike Pompeo has said Sen. Bob Menendez, D-N.J., and Senate Democrats are “putting the nation at risk” by holding up 65 of his department’s nominees.

Menendez has denied the charge and faulted the administration for not naming nominees.