In any other campaign, a labor union backing a Democrat for U.S. Senate would be routine.
But the first to line up publicly behind state Atty. Gen. Kamala Harris turned out to be the Los Angeles Police Protective League.
The announcement Wednesday underscored that a paramount goal for Harris is to keep Antonio Villaraigosa from entering the Senate race — or at least to make it more difficult for the former Los Angeles mayor should he decide to jump in.
Indeed, for Harris, the ritual of rolling out endorsements has appeared to be largely about fending off Villaraigosa, a fellow Democrat whose allies say he is leaning toward announcing his candidacy and could do so soon.
She started with two of the most prominent African Americans in Los Angeles politics: City Council President Herb Wesson, a longtime Villaraigosa ally, and county Dist. Atty. Jackie Lacey. Their support for Harris, who is black, suggested Villaraigosa cannot take for granted his once strong support among African Americans.
Next came a spate of Latino backers: Long Beach Mayor Robert Garcia, Assemblyman Jose Medina (D-Riverside), San Francisco City Atty. Dennis Herrera and former state Democratic Chairman Art Torres.
Villaraigosa, who would be California's first Latino senator, would need broad Latino support in Southern California to offset Harris' strength in the Bay Area.
Early endorsements can be the easiest to come by, and Villaraigosa could well poach support from Harris in San Francisco if he joins the race.
But the police union's move serves as a reminder that Villaraigosa's ties to organized labor have frayed, a potentially significant dynamic in a race between Democrats.
For example, the schools agenda that Villaraigosa pursued as mayor turned teacher unions into staunch adversaries.
Aggravating the natural tensions that any mayor faces with municipal unions, Villaraigosa had the misfortune of governing Los Angeles when the 2008 economic crisis struck, ravaging the city's finances. The police union's nearly 10,000 officers went without raises for three years on Villaraigosa's watch.
Law enforcement unions were no friend of Harris when she first ran for attorney general in 2010. Statewide, most of them backed her Republican rival after Harris, as San Francisco district attorney, refused to seek the death penalty in prosecuting the killer of city police Officer Isaac Espinoza.
But during her first four years as attorney general, Harris worked hard to build law enforcement support — and most of the state's police unions wound up backing her reelection.
Craig Lally, president of the Los Angeles Police Protective League, said he was moved that Harris had traveled far and wide to attend the funerals of slain officers.
"She's amazing with that," he said.
If other law enforcement unions join the league in backing Harris, it would bolster her law-and-order credentials.
That could prove particularly useful in a race against Villaraigosa, who has often boasted of expanding the Police Department's ranks by hundreds of officers when he was mayor.
Since Villaraigosa announced last month that he was exploring a Senate run, he has spoken privately with many campaign consultants, fundraisers and political leaders.
In Washington on Wednesday, he got a public service award from the League of United Latin American Citizens, but dodged questions on the Senate contest. "I'm not going to make a comment about the Senate race until I have something to say," he said. "And right now, I don't have anything to say other than what I've already said."
Another challenge for Villaraigosa would be the Harris campaign team: Two of her top consultants, Ace Smith and Sean Clegg, ran Villaraigosa's mayoral races and are intimately familiar with his political and personal history.
Beyond lining up political support, Harris is trying to get a fundraising edge over Villaraigosa. Hollywood executives, including Showtime President David Nevins, were planning to gather with the attorney general at a house in Bel-Air on Wednesday for a Harris campaign reception, according to the Hollywood Reporter.
What Harris has not done in the month since she announced her candidacy is take questions on matters before the Senate, such as military action against the Islamic State terrorist group.
Last week Harris told reporters in Los Angeles she could not discuss politics in a state office building. And after an appearance at Facebook's headquarters this week in Menlo Park, an aide tried to block a San Francisco Chronicle reporter from taking video of Harris declining to talk about the Senate race.
"I'm sorry, she is in a hurry," the aide told the media scrum before Harris promised to answer questions another day.
Garry South, a Democratic strategist who has informally advised Villaraigosa, said Harris' delay in taking stands on federal issues risked making her "look like a lightweight."
"At some point," he said, "if you're running for U.S. Senate, you have to talk about issues that the U.S. Senate deals with, and not run away from reporters."
Harris campaign advisor Brian Brokaw said she "will be speaking about the Senate race in the very near future, and there is a long time ahead of us."
Times staff writers Noah Bierman in Washington and David Zahniser in Los Angeles contributed to this report.