Mayor Michelle Wu is wading into Massachusetts primaries big and small, backing a transportation advocate running for the statewide job of auditor, supporting a Boston planning agency aide to represent parts of Dorchester and Roxbury in the Legislature, and swinging behind the incumbent Suffolk County sheriff.

Wu’s endorsements in contested primaries could be seen as a test of her political power, or, at the very least, something for the chattering class to talk about in a city and state known for enjoying politics as sport.

Boston mayors have typically had a spotty win-lose record when they’re not on the ballot, even if they’re able to marshal their forces in the fundraising and door-knocking departments.

Two of Wu’s predecessors, Marty Walsh and the late Thomas Menino, won reelection by large margins but would sometimes back candidates whose opponents won the vote in Boston. (Menino backed Hillary Clinton, who lost to Barack Obama, while Walsh supported longtime incumbent Mike Capuano, who was handily ousted from Congress by Ayanna Pressley.)

In Wu’s case, the tallying will occur after Tues., Sept. 6, the day of the primaries. That’s when Chris Worrell, a former state Senate aide and Boston Planning and Development Agency (BPDA) official running for the 5th Suffolk House seat, faces off against Danielson “Donny” Tavares, a former state House aide who held a variety of top roles within the Walsh administration. They’re both on the Democratic ballot with perennial candidate Althea Garrison. Without a Republican opponent, the primary will likely determine who takes the oath of office at the State House in January.

Wu, who encouraged Worrell to run earlier this year, announced her formal endorsement at last Saturday’s Hewins Street block party, an annual celebration a few steps from Blue Hill Avenue. She praised Worrell as a community leader and “convener.”

“We’ve seen him everywhere,” Wu said. “I’ve been sitting back and watching to see how it’s unfolded. Now that he’s thrown his hat into the ring, I’ve been quietly cheering from afar, and I decided it’s time to get into the race, because this matters. Who we elect right now matters so much.”

Worrell’s older brother, District 4 Councillor Brian Worrell, joined them for the announcement, as did Salem Mayor Kim Driscoll, who is running for lieutenant governor, and interim Suffolk DA Kevin Hayden, who is seeking a full term. (Wu endorsed Hayden’s opponent, Hyde Park Councillor Ricardo Arroyo, back in May.)

While a number of local lawmakers are going with Worrell, Tavares has pulled in endorsements from the Ward 15 Democratic Committee, the Boston Teachers Union, and Laborers Local 223, which is headed by a Walsh relative.

Tavares was door-knocking in Dorchester when he received a phone call about Wu’s Worrell endorsement, just before Wu posted a note to Twitter. “Endorsements don’t hold a lot of weight in this community,” Tavares said, chalking up Wu’s move to a “you scratch my back, I scratch yours” style of politics.

He added that he believes Wu “holds a grudge” against members of the Walsh administration, since Wu and Walsh clashed repeatedly before Walsh left the mayor’s office for the Biden administration last year.

Days before her swing through Hewins Street, Wu jumped into another contested Democratic primary: In the auditor’s race, she backed Chris Dempsey, a transportation advocate who in 2015 helped fight off a plan for Boston to host the 2024 Summer Olympics. Dempsey is facing Methuen state Sen. Diana DiZoglio for the job, which entails auditing state entities at least once every two years for efficiency and effectiveness.

For her part, DiZoglio rolled out the endorsement of Congressman Stephen Lynch, who represents South Boston and the eastern half of Dorchester. She has also touted the backing of numerous unions. “Born to a 17-year-old single mom, she grew up housing insecure, cleaning houses and waitressing tables to pay her way through college,” Lynch said in a statement issued Monday. “She then became a public servant to fight for working families like ours. We need her lived experience in the halls of power.”

Separately, an outside group — funded by unions such as the National Association of Government Employees (NAGE) and the International Association of Firefighters, as well as former state Rep. Brian Dempsey, now a top lobbyist — reported this week spending $100,000 in digital advertising on her behalf.

On Aug. 9, Wu headed to Nubian Square for her endorsement of Chris Dempsey. “When corporations and special interest groups tried to bring the Olympics to Boston and send a $15 billion bill to the taxpayers, Chris spoke out, organized, and helped us all win,” she said.

“She’s been an ally and a friend for many years,” Dempsey told the Reporter afterwards. While he supported her 2013 City Council At-Large run, they first met in person during a 2014 trip to Taiwan. Wu, the daughter of Taiwanese immigrants, led the 10-person bipartisan delegation, which included the founder of a Miami lobbying firm, a member of the DC Young Republicans, an aide to US Sen. Elizabeth Warren, and Dempsey, then a consultant for Bain and Co.

The nine-day trip’s itinerary included meetings with top Taiwanese officials and tours of a former British Consulate compound, a night market, a brewery, and a high-speed rail station.

Wu was one of the first calls Dempsey made when he was considering a run for auditor in 2021, while Wu was waging her own campaign for mayor. She has encouraged other elected officials to support him, according to Dempsey, and joined him for a virtual fundraiser on Monday night.

“She’s pledged to be helpful in every way she can,” he said.

In her third endorsement in the span of a week, Wu on Tuesday said she’s voting for incumbent Sheriff Steve Tompkins as he seeks to fend off a challenge from a former top aide. “The things that were true about Steve from the first day we met working on the first campaign for Senator Elizabeth Warren are still true today; he is a passionate, dedicated servant of the people,” Wu said in a statement sent out by the Tompkins campaign.

Tompkins was first appointed to the job in 2013 to fill a vacancy and then elected to a full term in 2014.

His rival for the post, Sandy Zamor Calixte, was first hired in 2006 and became chief of external affairs and communications in 2014.

Seth Daniel and Michaela Brant contributed to this report.