The relationship between the Denver police union and Chief Robert White has hit a new low point.

On Tuesday, the Denver Police Protective Association, which represents rank-and-file officers in collective bargaining, announced that its membership had passed a “no confidence” vote on the chief.

“The PPA did not undertake this survey lightly and has made diligent efforts over the past year to improve the performance and reputation of the police department and the relationship between the rank-and-file officers and the police administration,” said Nick Rogers, the union’s president.

The union has never held a no confidence vote on a chief in its nearly 100-year history, Rogers said.

Still, fewer than half of the department’s officers voted in the union’s survey. The union represents about 1,300 of the department’s more than 1,425 police officers, and 582 voted. Of those, 94 percent voted “no confidence,” Rogers said.

White released a statement through his department’s public information office, saying he respects the men and women who work in the department and is committed to doing what is best for them and the city.

“Having been a chief of police for 20 years, I understand that being chief can come with scrutiny from those who may disagree with decisions being made or fully understand all aspects of the position,” the statement said.

White and the union have had a rocky relationship since he was appointed chief in 2011. White was chosen by Mayor Michael Hancock to change the department’s culture.

“During my time in Denver, we have focused on improving our policies and culture, and these changes have been met with resistance by some,” White’s statement said. “However, it is my responsibility to make the right, and sometimes controversial, decisions for the betterment of our department and city.”

Hancock and city councilman Albus Brooks came to White’s defense.

In a statement, Hancock said, “After six years of the same message from the union, I am not surprised by the PPA’s opposition to Chief White’s efforts to change the Denver Police Department’s long-held culture, but continue to believe it’s the right move for Denver.

“I can tell you that when I speak to our officers, I hear a much different story than the one spun by the PPA today. I continue to hold great confidence in Chief White and our police officers to protect the health and safety of our people.”

Brooks fired off two tweets in response to the PPA’s vote, saying he had confidence in White and asking, “Wait is this the same union that voted to support @realDonaldTrump?”

The situation between White and the union has become more strained since January, when the union filed an open records request asking for a copy of a letter that was critical of Deputy Chief Matt Murray. The chief and Murray told the union, through the Department of Public Safety’s records coordinator, that they did not have the requested document.

But the union later obtained a copy of the letter from the district attorney’s office, which is where the letter originated.

The union asked the DA’s office to investigate White and Murray for possible criminal violation of the state’s open records law. District Attorney Beth McCann was critical of the two chiefs, and her investigative file revealed that others within the safety department believed they had been deceptive, but she declined to file charges against the two police officials.

An ongoing internal investigation is reviewing Murray’s handling of another internal investigation, which had been questioned by former DA Mitch Morrissey, as well as how White and Murray responded to the records request.

Most recently, the union has been asking about circumstances surrounding a hit-and-run crash that involved White. White’s police SUV was hit broadside by a minivan on a September morning. White pursued the minivan and rendered aid to the driver after the driver was ejected in a second collision. A criminal investigation into the minivan driver is pending.

But Rogers hinted Tuesday that White may not have followed police operating procedures that day, although he declined to offer specifics.

Earlier this month, White issued an apology to his department for what he described as a joke he had made to Aurora officers, who were the first to arrive at the crash scene.

In an attempt to break the tension, White said he joked about the rivalry between the two departments and hiring officers from Aurora. Denver7 first reported the story.

“In retrospect, I am concerned that what was meant as a humorous comment was offensive to some officers,” White’s email said. “For that, I sincerely apologize.”