In a stinging opening salvo to a possible mayoral race, Michelle Wu is throwing a major fundraiser in South Boston this week in the heart of her rival Ed Flynn’s turf.

Wu’s up to $1,000 a person fundraiser at legendary Southie restaurant Amrheins on Wednesday is a direct hit at Flynn, who is considering challenging the mayor in 2025.

The event is being billed as “South Boston for Mayor Michelle Wu” and is a clear sign Wu is looking to shore up potential political weaknesses as she gears for battle next year.

Flynn is a longtime South Boston councilor and the son of former Mayor Raymond L. Flynn. He has been a persistent critic of Wu’s policies especially over the last few months and has nearly $800,000 in his campaign war chest.

Wu’s fundraiser is hosted by former Superior Court Clerk Magistrate Mike Donovan, who the mayor appointed to the Massachusetts Convention Center Authority. Other names hosting the event are Kevin Lally, Tom Tinlin, Angel Feng, Steve Hollinger, Vincent Lau, Robert Morris, Nancy and Simon Pongratz, Eddie Regan, Emily Sy. Langdon White and Emily Yu, according to Wu’s campaign.

The fundraiser asks for donations up to $1,000, the legal maximum.

“The mayor has been hosting neighborhood events in South Boston since her first election in 2013, and is hosting neighborhood based fundraisers across the city,” Wu campaign spokesperson Julia Leja said in an email to the Herald.

Flynn, reached for reaction to the fundraiser in his home neighborhood, declined to comment.

But it has to irk Flynn a little to see Wu invade his turf.

Wu lost South Boston to opponent Annissa Essaibi George in 2021, one of Wu’s weakest showings in the city. She won the election with 62% of the vote and would be a heavy favorite if she goes through with plans to run for reelection.

Throwing the fundraiser Wednesday at Amrheins is a signal that she’s not willing to concede the neighborhood to Flynn if he chooses to run.

It could also be an intimidation tactic to get Flynn to stand down on his mayoral hopes.

Wu, who is pregnant with her third child, has repeatedly said she plans on seeking another term next year, but there are persistent rumors in City Hall that she will leave to the private sector instead.

Flynn, after initially trying to tamp down speculation, has most recently not ruled out running for mayor.

“I’m going to consider it at some point,” he told Politico on Sept. 18. “But I have a lot of work ahead of me before that.”

A Veterans for Flynn group formed over the last few weeks as a possible boost to the councilor’s mayoral hopes.

Josh Kraft, son of New England Patriots owner Robert Kraft, is also considering a mayoral bid.

But Flynn has gotten the most attention lately for his sharp criticism of the Wu administration. He has called for an investigation into why Boston school buses have been so late getting kids to school, and cited “significant public safety challenges” faced by the city, especially around Boston Common and Downtown Crossing.

He has called on Wu to hire more than 400 new Boston Police officers.