Ilhan Omar faces a primary challenge in her Minnesota House district.

Representative Ilhan Omar, one of Congress’s most prominent lawmakers, is facing four Democratic primary challengers in Minnesota as she seeks her third term, making her the latest member of the progressive group known as the “squad” to defend her seat this year.

Ms. Omar, whose election in 2018 shook up the Democratic establishment, is favored to win her primary. She has racked up endorsements from Democratic state and federal lawmakers and has been a prolific fund-raiser, hauling in more than $2.3 million in total contributions, according to the latest federal elections filings. If she gets the nomination, she would enter the general election with nearly $500,000 cash on hand.

But she is facing a strong centrist opponent in Don Samuels, a former Minneapolis city councilman and school board member. Mr. Samuels has the support of some of the Democratic establishment and Mayor Jacob Frey of Minneapolis. Mr. Samuels has raised more than $1 million and has more than $250,000 cash on hand, according to federal filings.

Ms. Omar, 39, has become a powerful voice on issues like racial justice and police reform. But she has been cast as divisive by her opponents and has at times found herself at odds with the Democratic establishment. Central to her primary clashes has been the issue of policing, as calls for reform have reverberated in Minneapolis since George Floyd was killed by the police in 2020, sparking national uproar over the treatment of Black Americans by law enforcement and the nation at large.

Last year, Ms. Omar supported a ballot measure to replace the Minneapolis Police Department with a new Department of Public Safety. Minneapolis voters struck it down. Mr. Samuels, who campaigned to defeat it, has told The Star Tribune that Ms. Omar’s support for the measure motivated him to run against her. He also notes that he was among eight Minneapolis residents who successfully sued to increase the number of officers.

Ms. Omar’s other opponents include A.J. Kern, Albert T. Ross and Nate Schluter, all of whom are considered nominal challengers and have raised little, if any, funds.

On the Republican side, Cicely Davis is expected to emerge as the nominee. Ms. Davis, who has the endorsement of the state’s Republican Party, served as the state director of BLEXIT Minnesota, an organization founded by Candace Owens, a far-right firebrand, to encourage Black voters to leave the Democratic Party. Ms. Davis has raised $2.2 million and ended the cycle with more than $100,000 cash on hand, according to federal filings.

Two members of the “squad” — Representatives Alexandria Ocasio-Cortez of New York and Ayanna Pressley of Massachusetts — did not draw any primary challengers this cycle. In Ms. Ocasio-Cortez’s case, that might have been in part because of her large fund-raising haul, a total of more than $10.2 million. Two other “squad” members, Representatives Cori Bush of Missouri and Rashida Tlaib of Michigan, recently beat back their primary challengers. A sixth member, Representative Jamaal Bowman of New York, is facing three primary challengers later this month.

Ms. Omar was the first woman of color elected to Congress from Minnesota, as well as one of the first two Muslim-American women elected to Congress. She is a favorite of progressives and beat her last well-financed challenger, Antone Melton-Meaux, a lawyer and self-described progressive, by 20 percentage points.

He drew the backing of pro-Israel groups and centrist Democrats who saw Ms. Omar’s election as a proxy fight over the Democratic Party’s direction on Israel policy. Pro-Israel groups also spent heavily against Ms. Tlaib, who has condemned Israel over the conflict with Palestinians and voiced support for the Palestinian cause.