Boston mayors have long fought with Beacon Hill. Wu is taking her battle to the ballot.

When Michelle Wu took the microphone at a Brighton restaurant last Tuesday night, she was six miles from the Massachusetts State House. But she may as well have been speaking to state Senate leaders face-to-face.

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“We need the state Senate not to be holding us back, not to be delaying, not to be throwing up more obstacles,” Wu told a cheering crowd, who snacked on tequeños and tostones in the Venezuelan restaurant’s crowded back room. “We cannot wait for action. We cannot wait for progress.”

Wu delivered her manifesto in formally backing Daniel Lander, her one-time aide vying to unseat state Senator William Brownsberger, the chamber’s third-ranking Democrat. But it gave voice to a growing exasperation in City Hall over those in the other government building up the hill.

While Wu has many allies in the Massachusetts House, her deteriorating relationships in the Senate have led her here, dropping the veil and endorsing first-time candidates running against those she views as thwarting one of her biggest priorities: a plan that would shift more of the city’s tax burden onto commercial real estate.

Perhaps no issue has more strikingly animated Wu’s bitter, nearly two-year-long battle with powerful Democrats in the Senate. It’s also the driving force behind her political moves now. She has endorsed both Lander and Latoya Gayle, one of the Democrats challenging Senator Nicholas Collins, another Wu antagonist.

Her decision to directly insert herself into races against sitting Democrats in her own city, and her unflinching public portrayals of Senate leadership, have prompted even her allies to question her tactics. Wu, fresh from a romp to reelection, is awash in political capital, but she also risks inviting further isolation from the power brokers who pull the legislative levers.

Wu said she isn’t worried about blowback.

“There are a lot of egos in politics,” she said in a recent interview inside her City Hall office. “If the top criteria was to make sure that we get along with everyone and prioritize comfort in conversations and relationships, then we wouldn’t do anything at all.”

Wu repeatedly pushed her tax measure through both the City Council and the House, and in 2024, negotiated a compromise version of the legislation with business and real estate group leaders, who had initially opposed her plan.

But those organizations later walked back their support after data showed that residential tax bills would not jump as high as her administration had previously estimated, and feared commercial landlords would bear too much of the burden. State senators then killed the bill amid staunch opposition from Collins, and then the chamber denied it again this past winter as Collins and Brownsberger pushed alternative proposals.

“We were all disappointed by how that all played out,” said Representative Aaron Michlewitz, a North End Democrat, close Wu ally, and the House budget chief, who said his own property taxes have gone up the past two years. “What was very frustrating was that the bill could not even be advanced.”

That fight informs Wu’s new one. Wu said she personally didn’t recruit Lander or Gayle, but she said the chamber’s moves to block her bills — and their “comfort of maintaining the status quo” — are driving why she’s targeting two sitting Democrats who represent her city.

“The question for all of us who are in leadership roles is: ‘Are we going to throw up our hands and say this is bigger than we can manage?’ Or are we going to roll up our sleeves and try to find any and every way to make a difference for our constituents,” Wu said. “That’s what every election cycle is about.”

Senate leaders dispute that they’re the problem. Brownsberger said he is a collaborative partner on many issues, and pointed to endorsements he’s gotten from Governor Maura Healey, Attorney General Andrea Campbell, and several state representatives and local officials.

“Most other local officials are endorsing me because they know what a great partner I am,” said Brownsberger, a Belmont Democrat who represents parts of Boston.

A spokesperson for Senate President Karen Spilka said lawmakers have delivered a myriad of progressive policies that benefit Boston and other residents alike, be it funding for tuition-free community college or free school meals.

“The question isn’t whether Boston should have a voice. It already does,” said Gray Milkowski, the Spilka spokesperson. The question, he said, is “whether every proposal that emerges from City Hall should become state law, or whether legislators have a responsibility to weigh different perspectives and sometimes take a different approach.”

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Multiple efforts to reach Collins were unsuccessful.

Wu is not the first mayor to run into speed bumps on Beacon Hill, nor is she the first to pick political battles at the State House, where local officials are reliant on legislative approval for changes big and small.

While Wu has had some success, such as helping realize a dramatic expansion of liquor licenses in the city and getting her own appointee on the MBTA board, Boston has far less control over its own fate in the State House than other major cities across the country.

Tom Menino, the late and longest-serving Boston mayor, used to call members of the city’s legislative delegation to the mayor’s residence atthe Parkman House or into his office overlooking Faneuil Hall to talk through his legislative agenda.

In his memoir, Menino recounted “haranguing” resistant state legislators to support in-district charter schools: “I put on my hot-under-the-collar act.”

“Hanging up on one rep, I told my press secretary Dot Joyce, ‘I’ll bet I gave him brown pants!’” he wrote.

Former mayor Martin J. Walsh,who served in the state House from 1997 to 2014, ran a similar ground game as mayor, with the insider knowledge of a veteran legislator.But even he had setbacks, too, fighting unsuccessful battles to secure ambitious tenant protections, protect seniors from being displaced due to rent hikes, and move revenue to help fund Boston Public Schools.

Neither Menino nor Walsh played their cards like Wu is, however, in backing upstart challengers to sitting Democratic state lawmakers.

“You can point a finger at the Legislature and say, ‘I tried my hardest, but these people wouldn’t budge.’ You can work back channels and find a compromise,” said Keith Mahoney, who served as City Hall’s director of state relations under Menino. “Or you can stick to your guns and re-file the bill and try a different approach.”

Boston lawmakers also view Wu differently than they did Menino or Walsh, said state Representative Russell Holmes, a Mattapan Democrat who was first elected in 2010. Menino and lawmakers had a “father-son” relationship where he “pushed hard on us” to pass his legislation, he said, while Walsh felt like more of an “older brother” with the experience on Beacon Hill.

“She is making things harder in the Senate by running people against senators. It puts us all in the box when she does that,” he said. “The culture in the Legislature isn’t to go against your colleagues. … She doesn’t understand that.”

State Senator Lydia Edwards, a Wu ally and former Boston city councilor, openly wondered if Wu’s endorsements constitute “normal politics” or “a division that can’t be mended.”

To be sure, the mayor’s not writing off all Beacon Hill incumbents being challenged in their primaries this year.

In January, she endorsed state Senator Mike Rush, a moderate West Roxbury Democrat facing a progressive primary challenger in Hyde Park attorney Persis Yu. The race marks Rush’s first primary challenge since 2008.

While Wu has faced uphill battles in the state Senate, the House is a different story. Speaker Ron Mariano, a Quincy Democrat; Michlewitz of the North End; and the chamber’s majority leader, Mike Moran of Brighton, all live in Greater Boston, and have had long-standing relationships with the mayor.In the Senate, Spilka is from Ashland in the MetroWest region, and Senate budget chief Michael Rodrigues is from Westport, near the Rhode Island border.

Wu said, in her experience, it’s not geography but added that House lawmakers have shown more interest in collaborating. On the property tax issue, she said she personally called all 40 state senators.

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“There was outright rejection or silence,” she said.