BOSTON (SHNS) – Labor attorney Shannon Liss-Riordan will officially launch her campaign for attorney general on Tuesday, entering a potentially growing field of candidates on the Democratic side looking to succeed Attorney General Maura Healey as she makes her bid for governor.

Liss-Riordan’s interest in the race if Healey vacated the seat was well-known. The former U.S. Senate candidate will make the formal announcement at noon at the Ironworkers Local 7 hall in South Boston when the union also plans to endorse her candidacy, according to her campaign.

Healey last week announced that she had decided after two terms as attorney general to mount a bid for governor, opening up a coveted statewide office that has drawn interest from at least a trio of Democrats.

Liss-Riordan, 52, is a partner at Lichten & Liss-Riordan in Boston, and has built a reputation filing lawsuits against major corporations on behalf of workers, including Starbucks, FedEx, American Airlines, GubHub, Doordash and others.

The Brookline resident has also been a prominent voice in the fight against a question ticketed for the ballot in November that would allow tech companies like Uber and Lyft to continue to classify their drivers as independent contractors instead of employees in exchange for some benefits like paid sick time.

“They know that their days are numbered, so what they’re doing is they’re coming here to you and asking you to change Massachusetts law to legitimize what they’ve been doing all these years and not have to provide all the protections and rights that all other employees in Massachusetts have,” Liss-Riordan told lawmakers at a committee hearing in October.

Liss-Riordan previously brought a class action lawsuit against Uber on behalf of drivers in California and Massachusetts, arguing the company misclassified its employees as independent contractors, wrongly denying them access to wages and benefits guaranteed for other workers. That lawsuit led to a $20 million settlement.

In entering the race, Liss-Riordan joins the 2018 Democratic nominee for lieutenant governor Quentin Palfrey, a former Obama administration official and lawyer in the attorney general’s office who is currently working in digital privacy.

Palfrey is expected to make a formal campaign announcement soon, but in welcoming Healey to the governor’s race said he looked forward to building a “grassroots campaign for AG that respects, empowers, and includes people from across the state.”

Andrea Campbell, the former Boston city councilor who ran for mayor in 2021, also is seriously considering a bid to become the state’s top law enforcement officer, according to sources close to her.

Liss-Riordan grew up in Texas and earned her bachelor and law degrees from Harvard University. She opened a campaign account in December in anticipation of a possible run, and reported raising $159,131 before the end of the year, with attorney contributions constituting a big share of her donations.

In 2019, Liss-Riordan began running for U.S. Senate in what would have been a challenge to incumbent U.S. Sen. Edward Markey, but following former Rep. Joe Kennedy’s subsequent entrance into that race she ended her campaign well before the Democratic primary.

While in that race, she called for an outright repeal of the Second Amendment after deadly mass shootings in Texas and Ohio put a spotlight on gun control, and backed standard minimum wages for tipped workers.

There are currently no Republicans running for attorney general, and Democrats have controlled the office since 1969 when Elliot Richardson left to join the Nixon administration.