While the endorsement of the 3,600 member police union is hardly a guarantee of victory, it is a welcome nod for independent mayoral candidate David Catania. (Mary F. Calvert for The Washington Post)

The Democratic mayoral nominee will not have a monopoly on labor endorsements in this year’s D.C. mayoral race, it turns out.

While Muriel Bowser has won the backing of organized labor’s main umbrella organization in the city, as well as nods from several major individual unions, independent rival David A. Catania is set to pick up a coveted endorsement from the union representing rank-and-file D.C. police officers.

“David Catania is the most qualified candidate in the race,” said Delroy Burton, the police union’s chairman, speaking ahead of a formal announcement set for Wednesday morning in Southwest. “I think he has the background and the understanding necessary to manage the complexities of District government.”

The endorsement comes after a unanimous vote from the union’s 20-member board of directors, Burton said.

The backing of the 3,600-member police union has been a hit-or-miss affair over the past decade, politically speaking. The union backed losers Carol Schwartz in 2002 and Linda Cropp in 2006; it endorsed Vincent C. Gray in 2010 only to clash with him almost immediately after his election after he reappointed Cathy L. Lanier as police chief without the union’s input. In this year’s Democratic primary, it was Tommy Wells, not Bowser, who won support from the boys and girls in blue.

Still, candidates would rather have the police endorsement than not, and for Catania it sends a especially valuable signal about his viability in an overwhelmingly Democratic city, if not his broader support among leaders of organized labor.

“It’s a vote of confidence in David Catania, and our campaign,” said Ben Young, his campaign manager. “They clearly believe he is the best person to lead the city and the police department.”

Given the union’s longstanding tensions with Lanier, its Bowser snub might not be all that surprising: Bowser has spoken highly of Lanier and has hinted the chief will be welcome to stay on should Bowser win.

Burton said that neither Bowser, in an interview conducted before the primary, nor Catania said whether they would keep Lanier. The union, Burton said, did seek assurances from the candidates that the union would be involved in major decisions.

Young said Catania has kept to his policy of not discussing personnel decisions before the election but told the union he “would listen to all parties” in making such decisions.

The union’s backing of Catania, Burton said, mainly was rooted in other factors, including corruption in government and ongoing tensions between police management and the union.

“Given what’s happened in the city over the last four years with [Mayor Vincent C. Gray] and some members of the council, we need to change our approach to the way we run the government,” Burton said, adding that he has been impressed by Catania’s grasp of labor issues as a D.C. Council member.

Bowser, he said, would be “a continuation of the machine politics we have had, and that’s not a good thing.”

The police officers’ Catania nod heralds an unusual split between two major public safety unions; leaders of the union representing rank-and-file firefighters stood with Bowser last week as she accepted the endorsement of the Metro Washington Labor Council AFL-CIO.