D.C. Police Union Chairman Delroy Burton announces the endorsement. (Mike DeBonis /The Washington Post)

In his 17 years as a D.C. Council member, David A. Catania has built a reputation mainly in the realms of health, education and fiscal matters. Now, as a mayoral candidate, he is seeking to more firmly establish some public safety bona fides.

Those efforts got a boost Wednesday with an endorsement from the union representing 3,600 rank-and-file D.C. police officers, whose leader called Catania “the most qualified candidate in the race.”

“I think he has the background and the understanding necessary to manage the complexities of District government,” said the union chairman, Delroy Burton, before an announcement Wednesday in Southwest Washington, not far from where six people were shot this month.

Catania said the location was chosen to emphasize “the importance of having a well-trained, highly functional, highly supported police department.”

“As a candidate for mayor, you cannot ask for a more important endorsement,” he said. “These are the individuals who have their lives at risk every day, and their confidence . . . means a great deal.”

Before the police union weighed in, council member Muriel E. Bowser (Ward 4), the Democratic nominee for mayor, had collected every endorsement made by organized labor, including from unions representing firefighters and other city employees, as well as the Metro Washington Labor Council AFL-CIO.

The police union’s backing also raised the question of whether Catania would keep Cathy L. Lanier, the city’s police chief since 2007. Lanier has won high ratings in the polls while repeatedly clashing with union leaders, and Bowser has hinted that the chief would be welcome to stay on in a Bowser administration.

Joaquin McPeek, a Bowser campaign spokesman, said Wednesday that, if elected, Bowser “looks forward to continuing to work with Chief Lanier and the great men and women of the Metropolitan Police Department.”

Catania stuck to his policy Wednesday of not commenting before the election on particular personnel moves, saying any pronouncement would be unfair to Lanier and the current mayor, Vincent C. Gray (D). He tempered his praise for Lanier with calls for the department to improve its efforts to recruit officers and retain those in its ranks.

“I’ve always been very supportive of her, and I think she has done a fantastic job,” he said. “Now, at the same time, I think we all have to look for ways to constantly improve ourselves and improve our mission. That’s not an indictment of her; it’s just an acknowledgment that we can do better.”

Lanier has said she hopes to stay on as police chief under the new mayor. In a television interview Wednesday, she said that retaining her department’s roughly 3,900 sworn officers continues to be a focus and concern. Catania said he would aim to enlarge the department to 4,000 officers.

Independent candidate Carol Schwartz, a former council member who won the police endorsement during previous council and mayoral campaigns, suggested in a statement Tuesday night that Catania had pledged to remove Lanier in exchange for the union’s endorsement.

Catania called the claim “absolutely outrageous,” and Burton said Schwartz was “flat-out wrong.”

The police union’s backing has been a hit-or-miss affair, politically speaking. The union backed mayoral losers Schwartz, in 2002, and Linda Cropp, in 2006; it endorsed Gray in 2010 but clashed with him almost immediately after he was elected and reappointed Lanier as chief without the union’s input. In this year’s Democratic primary, it was council member Tommy Wells (Ward 6), not Bowser, who won the union’s support.

The union did mailings in support of Wells, but Burton said Wednesday that it was still up in the air as to what efforts would be waged on Catania’s behalf. “We’re going to discuss what the options are,” he said.

The endorsement alone could serve to reassure voters concerned mainly about crime; Catania has focused his campaign pitch on education, often to the exclusion of other issues.

“The intersection between education and public safety is obvious,” he said Wednesday when asked about his public safety platform. “When so many of our young people are not properly educated, they often choose lives in the illegal economy, for lack of a better term. What we have to do is make sure our education system is up and functioning. I think that is a public safety platform.”