BOSTON — Republican John Deaton, a former U.S. Marine and cryptocurrency attorney, announced Monday that he is challenging Democratic U.S. Sen. Elizabeth Warren as she runs for her third term in office.

Deaton, 56, who was born in Detroit and recently moved to Massachusetts, released a campaign video Monday highlighting his hardscrabble upbringing, his years in the Marines serving as a judge advocate at Marine Corps Air Station in Yuma, Ariz., and his career as a lawyer in part representing mesothelioma victims.

Deaton cast himself as a fighter for the working and middle classes.

“I fought for the little guy. I took on the greedy corporations and the heartless insurance companies, and I won,” Deaton says in the video. “I am running for U.S. Senate to continue my life’s mission to shake things up for the people who need it most.”

Deaton, a virtual unknown in Massachusetts politics, faces a steep climb against Warren, 74, a former Harvard law professor who has twice won a Senate seat but came in third in Massachusetts in her 2020 bid for president.

Warren currently has more than $3.9 million in her campaign account.

If elected in November, Deaton said he would take on the insurance industry and drug companies for more affordable health care, work across the political aisle to help solve the migrant crisis, fight inflation and push for term limits for those he described as “career politicians.”

A spokesperson for Warren says she’s taking nothing for granted and “has a strong record of delivering for working families and continues to fight hard for the people of Massachusetts.”

Warren released a report Tuesday detailing the more than $50 billion in federal support for Massachusetts that she said she has secured during her time in the Senate, including funding for roads and bridges including the Cape Cod bridges; $185 million in broadband funding for high-speed internet access; and $270 million in grants to firefighters.

Deaton grew up in Detroit’s Highland Park neighborhood, which he described as one of the poorest and most dangerous in the country. He said he was one of six siblings whose mother held the family together with the help of food stamps, welfare, and odd jobs.

He said his youth was marked by violence, physical and sexual abuse, and what he described as a survival-first mentality.

Deaton said he became the only member of his family to graduate high school, went to college at Eastern Michigan University, where he was diagnosed with testicular cancer and underwent treatment while still pursuing his degree. He was accepted into Boston’s New England School of Law in 1992.

While in law school, Deaton enlisted in the Marines and was medically retired in 2002 following a non-combat injury, starting his own law firm in Rhode Island,

As an attorney, Deaton said he has represented mesothelioma, cancer and asbestos victims.

Deaton has also delved into cryptocurrencies.

He said he was drawn to the technology by remembering how his mother relied on what he described as “predatory inner-city check cashing operations” and was intrigued by cryptocurrency’s ability to help the underprivileged and unbanked.

Warren has been a prominent backer of regulating cryptocurrency, calling it “the preferred tool” of money launderers and other criminals.