As the Democratic primary for attorney general heats up in the final days before the Sept. 6 election, labor attorney Shannon Liss-Riordan secured three prominent endorsements, raising the stakes in what is increasingly looking like a two-woman race.

Senator Elizabeth Warren, Boston Mayor Michelle Wu, and former acting Boston mayor Kim Janey endorsed Liss-Riordan on Saturday afternoon, on the first day of in-person early voting across the state.

In doing so, Wu and Janey snubbed their one-time colleague, former Boston city councilor Andrea Campbell, who is also running for attorney general and has secured the endorsements of Massachusetts’ other senator, Edward J. Markey, as well as several members of Congress and current Attorney General Maura Healey, the presumptive Democratic nominee for governor.

Liss-Riordan said more than two decades of experience as a lawyer representing working people sets her apart.

“Put my resume side by side with that of the other candidates in this race, and ask yourself, if you were hiring a lawyer for yourself, who would you hire as your lawyer?’’ she said to press.

Just hours before Liss-Riordan’s endorsement event, Campbell hosted her own event, an early voting kickoff with Healey and Representative Ayanna Pressley of Boston, where they were cheered on by supporters outside a Dorchester community center.

“We have 10 days to go . . . they’re coming for us,’’ Campbell said at the event. “That’s OK. There’s so many people undecided. It’s going to require us to phone bank like we’ve never phone banked before. To door knock like we’ve never door knocked before. To continue to get our people out to vote. When we do, we will win this race.’’

Healey, who is often aligned with Senator Elizabeth Warren, said she knows best what the state needs in an attorney general.

“I have been the attorney general for eight years. I have worked in that office for 15,’’ the South End Democrat said at the event. “I know what that office needs. I know what an AG needs to do and to provide. That’s why I’m with Andrea Campbell.’’

Later in the afternoon and across town at the Central Library in Copley Square, an early voting site, Liss-Riordan and the three women endorsing her entered to the tune of “Ain’t Got Far to Go’’ by Jess Glynne and the cheers of supporters.

“Are we ready to put a people’s champion in the AG’s office?’’ Wu called out.

The three said Liss-Riordan is a lawyer who has taken on big corporations and won victories for working people.

“She doesn’t just fight, Shannon wins,’’ Warren said.

Warren said Liss-Riordan turned down lucrative opportunities in corporate law to take on the “hard cases’’ against major corporations, including FedEx, Starbucks, and Uber. Liss-Riordan has put more than half a billion dollars into working people’s pockets, Warren said.

Liss-Riordan has drawn criticism for the shares of the lucrative settlements she has sought in her cases, which have totaled millions of dollars.

The candidate said at the event that she’s spent her legal career “in the trenches, fighting for those whose voices need to be heard.’’ She has been endorsed by the Massachusetts AFL-CIO, and she said she also has the support of more than 50 individual unions representing half a million working people across the state.

“The people of Massachusetts want their leaders to fight for them,’’ she said. “They want their attorney general to be a seasoned, experienced lawyer who knows how to use the legal system to make a difference in people’s lives.’’

The dueling events, and the competing high-powered endorsements on display, highlight the extent to which the attorney general race has become the contest to watch this political season. The AG primary contest has narrowed in recent days, with recent polling showing Liss-Riordan and Campbell in a near dead heat.

While Campbell polled ahead of Liss-Riordan for months, the labor attorney — bolstered by substantial, largely self-financed spending on direct mail, radio, and TV ads — has surged in the past few months.

According to a recent poll of likely voters by MassINC Polling Group, Campbell, who retained name recognition from her unsuccessful Boston mayoral campaign last year, leads Liss-Riordan by just two percentage points — 28 percent to 26 percent — well within the poll’s margin of error. Quentin Palfrey, a former assistant attorney general and the Democrats’ 2018 lieutenant gubernatorial candidate, drew 10 percent.

The poll also found that a third of voters haven’t made up their minds about the race.

Mary Cahill, 59, of Back Bay, is one such voter. She stopped to check out Liss-Riordan’s event after browsing the Boston Open Market at Copley Square with her husband.

“I’m aware of some of her class-action lawsuits representing underprivileged people,’’ she said. “That’s appealing.’’

The new endorsements show a split of typical alliances, with Warren departing from Pressley, who has been in the trenches with the senator in fighting for student loan forgiveness among other issues, and Healey, whom she has endorsed in her race for governor and has worked alongside to take on predatory student loan servicers.

Campaign finance records show that Liss-Riordan has supported Warren in her past races. In 2017, Liss-Riordan and her husband, Kevin, each made a $5,400 contribution to Warren’s political committee as well as $4,400 in donations to her campaign. In 2019, Liss-Riordan donated $2,800 to Warren’s presidential election campaign. Liss-Riordan donated $35,500 to the Democratic Senatorial Campaign Committee in 2020, and donated $10,000 more in 2022.

In response to a question about the split, Warren said, “It’s very lucky that there are so many extraordinary people who want to be in public service at a lot of different levels.’’

She added, “I’m here just to tell the people of Massachusetts how I see it, and that’s the best I can do.’’

Kate Selig can be reached at kate.selig@globe.com.

Samantha J. Gross can be reached at samantha.gross @globe.com.