Sen. Tammy Duckworth (D-Ill.) said Wednesday, July 8, she will continue to put a hold on 1,000 military promotions until she gets an explanation from President Donald Trump’s defense secretary on Lt. Col. Alexander Vindman’s retirement.

Duckworth last week announced that she would block Senate confirmation of 1,123 senior military officers until she received a written assurance from Defense Secretary Mark Esper saying that he would not block Vindman’s promotion to colonel.

Vindman, who testified against President Trump in House impeachment hearings during which he admitted providing inaccurate information, was fired in February from the National Security Council and escorted off the White House grounds.

On Wednesday, Vindman announced he was retiring from the Army with his lawyer accusing President Trump of bullying and retaliating.

Duckworth said in statement Wednesday that she would continue to hold up the promotions until Esper provided a “transparent accounting” of what her office described as a “disgraceful situation.”

“Lt. Col. Vindman’s decision to retire puts the spotlight on Secretary of Defense Mark Esper’s failure to protect a decorated combat veteran against a vindictive commander in chief,” Duckworth said.

“Secretary Esper’s failure to protect his troops sets a new, dark precedent that any commander in chief can interfere with routine merit-based military promotions to carry out personal vendettas and retaliation against military officers who follow duly authorized subpoenas while upholding their oath of office and core principles of service,” she wrote.

But Esper had signed off on Vindman’s promotion to colonel on Monday, reported Reuters. The recommended promotion was “due to be sent to the White House in the coming days,” according to a senior U.S. defense official.

Duckworth, who was the first Thai-American woman elected to Congress, has emerged as a contender to be presumptive Democratic presidential nominee Joe Biden’s running mate. She is being vetted by the Biden campaign and would be the first woman of color nominated for that high office if chosen.

“The Biden campaign have their own process that they’re going through. And I’m sure Vice President Biden will pick the right person to be next to him as he digs this country out of the mess that Donald Trump has put us in,” Duckworth told reporters.