High-profile workers' rights lawyer Shannon Liss-Riordan will challenge U.S. Sen. Ed Markey in the 2020 Democratic primary.

The 49-year-old Brookline resident launched her campaign against the longtime member of Congress on Monday, presenting herself as a champion for women, blue-collar workers and families and vowing to break the "endless cycle" of maintaining the status quo.

"Some people have called me the sledgehammer," Liss-Riordan says in a launch video. "Others say I'm corporate America's worst nightmare. My kids just call me mom."

Liss-Riordan is best known for leading a class-action suit by workers against Uber that began in 2013. The ride-hailing giant settled with its workers for $20 million earlier this year. The attorney has also won cases against Starbucks, Harvard University, FedEx and American Airlines.

"I'm in this race in order to offer voters in Massachusetts a choice," Liss-Riordan told WBUR. "I have been a tireless worker and a tireless advocate for the rights of working people, and I see the issues that are happening in the workplace are only fueling income inequality — which is growing to maddening levels."

She's currently a partner at Lichten & Liss-Riordan law firm in Boston.

Markey has represented Massachusetts since 1976, when he began his first term as U.S. representative for the state's 7th District. He was elected to the Senate in 2013.

Markey said Monday that he won't let the fact that he has a primary challenger change the way he does his job or approaches his re-election.

"Good policy is good politics," Markey said, after addressing business leaders at a New England Council luncheon at the Boston Harbor Hotel.

Markey's campaign on Monday announced several hires for his political team ahead of the official launch of his re-election effort. Markey has $3.5 million cash on hand, his campaign said.

With reporting by WBUR's Laney Ruckstuhl and Kimberly Atkins, and State House News Service