Another challenger for Michelle Wu? Developer Thomas O’Brien considering jump into mayoral race.

A person close to O’Brien said he has been fielding calls from residents and business leaders expressing concerns about the city’s fiscal health, rising property taxes on seniors and homeowners, the lack of affordable housing, and the quality of Boston Public Schools, and that they have encouraged him to consider putting his hat in the ring.

Typically, business leaders, especially real estate developers, back the incumbent because they have to work closely with the sitting mayor and need approvals from City Hall for their projects. Indeed, HYM is currently leading the massive Suffolk Downs redevelopment on the East Boston-Revere line, which is still in early phases, and has buildings remaining to go on its redo of the Government Center Garage. HYM also won the bid to develop the city-owned Parcel 3 on Tremont Street in Roxbury into life sciences labs and housing.

But this election cycle could be different, with the commercial real estate community so frustrated by Wu’s policies that some say they will do anything to make sure she doesn’t get reelected — even apparently running against her.

Developers have opposed Wu’s efforts to increase affordable housing requirements and expand green building codes, as well as her attempts to cap residential rent hikes and raise commercial property tax rates. Taken together, developers have said her policies are driving up building costs and discouraging new construction.

While it had been an open secret for a year that Kraft was eyeing a mayoral challenge, news of O’Brien’s potential candidacy took many people by surprise. Like Kraft, O’Brien has never run for public office before.

It is likely O’Brien has been waiting in the wings to see how Kraft would fare.

Wu’s first major challenger was off to a solid start, collecting close to $300,000 in donations in February, and the first independent poll by Emerson College conducted in late February indicated that Wu was far from a shoo-in. The mayor led Kraft with 43 percent support to his 29 percent, while a significant proportion of voters, 24 percent, were undecided.

But then last week Kraft lost momentum after Wu had the best week of her political life after appearing before a Republican-led Congressional committee to defend Boston’s sanctuary city status. She, by many accounts, not only represented the city well but created viral moments of her own clapping back at anti-immigrant sentiment.

That could create an opening for O’Brien if voters think Kraft may have peaked. Kraft and O’Brien would likely vie for moderate voters who want the city to show more fiscal restraint and not raise taxes. And like Kraft, O’Brien could tap his vast network, both in the business community and in neighborhoods around the city where he has built projects, to fundraise and build support.

“Wow,” observed Larry DiCara, a Boston real estate attorney who served as a longtime city councilor before running unsuccessfully for mayor in 1983. “He’d be a very substantial candidate if he decides to run. It makes it more difficult for Kraft to put the pieces together … this changes the entire ballgame.”

A spokesperson for the Kraft campaign declined comment. But a Wu campaign spokesperson took aim at both challengers, tying them together as candidates favored by big real estate interests.

“It is clear some developers are willing to do whatever it takes to buy this office,” according to a statement from the Wu campaign. “It seems like Josh Kraft is not turning out to be what they expected and now they are shopping for a new option.”

Like Kraft, O’Brien is well known in business and civic circles in Boston. A father of five and a Brown University graduate, he serves on the board of the Pine Street Inn and Rose Kennedy Greenway Conservancy. He is also a member of the Global Leadership Council of the Anti-Defamation League of New England. O’Brien grew up in Scituate and Andover and now lives in downtown Boston. And his brother, Bill O’Brien, is head football coach at Boston College.

Thomas O’Brien spent five years in the 1990s working under Menino at the city planning and development agency, then known as the Boston Redevelopment Authority, including two years as its director. O’Brien resigned following a scandal involving a top BRA aide who purchased a subsidized condo intended for low-income families.

Since then, O’Brien has remade himself into one of the region’s most prolific developers and a business leader. He helped launch HYM in 2009, and the firm has played a key role in major, complicated projects, including Boston Landing in Brighton, NorthPoint in Cambridge, Bulfinch Crossing in downtown Boston, and Suffolk Downs.

Still, unseating an incumbent is no easy feat. That hasn’t happened in Boston since 1949, when Mayor James Michael Curley lost to John B. Hynes. Curley had just served time in federal prison for mail fraud, and instead of resigning, he chose to run for reelection.

Wu, a Harvard graduate and mother of three, is a savvy politician who has won multiple citywide elections, first as a city councilor at large and later as mayor in 2021. The Roslindale resident and progressive Democrat has shattered political barriers, becoming the first woman of color to serve as City Council president and the first woman and person of color elected as mayor of Boston.

O’Brien has not openly criticized Wu during her term as mayor. But in offering a statement to the Globe shortly after Kraft’s announcement, he seemed to outline the contours of a potential campaign.

“Boston is facing real challenges — rising taxes, a growing budget, and a housing shortage that needs action. Investments should reflect community priorities, like ensuring our students’ educational priorities are balanced with the need for high-quality sports facilities and other competing issues. Thoughtful planning and engagement matter,” said O’Brien. “We need someone who leads the way, but also is collaborative and works with residents and businesses to shape Boston’s future.”

Shirley Leung is a Business columnist. She can be reached at shirley.leung@globe.com.