PHOENIX — Democratic U.S. Rep. Ruben Gallego of Arizona made it official Monday: He’s running for U.S. Sen. Kyrsten Sinema’s seat in 2024.

Gallego has been an outspoken critic of Sinema, especially since she switched her affiliation from Democrat to independent last month.

The Marine veteran, who was elected to his fifth House term in November, has been teasing a Senate run for some time while building a campaign staff.

“I have been deeply humbled by the encouragement I have received from the people of Arizona, and today I am answering the call to serve,” Gallego said in a press release.

“I’m running for the U.S. Senate because the rich and the powerful don’t need any more advocates in Washington – but families who can’t afford groceries do. As a Marine, I never back down from a fight, and in the Senate I’ll fight to make sure every Arizonan has the same chance that I had at the American Dream,” Gallego said in a press release.

Another potentially strong candidate, Rep. Greg Stanton, took himself out of consideration last week, leaving Gallego as the clear Democratic primary favorite.

Gallego previously hired two consultants from Arizona Sen. Mark Kelly’s recent reelection victory. Gallego’s team also includes members of firms that worked on two other successful 2022 Democratic campaigns, John Fetterman’s in Pennsylvania and Raphael Warnock’s in Georgia.

He’s also been using attacks on Sinema to raise funds online.

“The problem isn’t that Sen. Sinema abandoned the Democratic Party – it’s that she’s abandoned Arizona. She’s repeatedly broken her promises, and fought for the interests of big pharma and Wall Street at our expense,” Gallego said in the press release.

Sinema, who became Arizona’s first Democratic U.S. senator in more than 20 years when she was elected in 2018, hasn’t confirmed that she will seek reelection.

“I’m not really thinking or talking about the election right now — although others are — I’m staying focused on the work,” she told KTAR News 92.3 FM’s The Mike Broomhead Show on Friday amid reports that Gallego’s announcement was forthcoming.

If she does run, Arizona could see a hotly contested three-way race in the general election.

No Republicans have thrown their hats into the ring yet, but the primary field could include the likes of Kari Lake, who lost to Gov. Katie Hobbs in the 2022 general election, and Blake Masters, who lost to Kelly.

U.S. Rep. Andy Biggs, Pinal County Sheriff Mark Lamb and Karrin Taylor Robson, who lost to Lake in the 2022 GOP primary, are also considered potential GOP candidates for Sinema’s seat.

Follow @KTAR923