Democrat in Arizona Will Seek Kyrsten Sinema’s Senate Seat

Representative Ruben Gallego, a progressive Democrat from Phoenix, announced on Monday that he would run for the Senate in 2024, setting up a potential face-off with Senator Kyrsten Sinema over her seat that could carry high stakes for Democrats’ control of the upper chamber.

Mr. Gallego, a 43-year-old former state lawmaker and U.S. Marine veteran, began his campaign with a video in which he declares his run to a group of fellow veterans at American Legion Post 124 in Guadalupe, Ariz., near Phoenix. In it, he highlights his humble Chicago origins and his combat experience in Iraq, and he pledges to fight to extend the American dream to more families.

“It’s the one thing that we give every American, no matter where they’re born in life,” he says, crediting belief in the dream for his own climb into the halls of Congress.

Ms. Sinema, whose opposition to key elements of her party’s agenda had angered Democrats, left the party in December and registered as an independent. Democrats in Arizona quickly turned their attention to her seat. It is expected that Ms. Sinema will seek re-election, but she has not yet announced her intentions.

In his campaign ad, Mr. Gallego sought to draw sharp contrasts between himself and Ms. Sinema, taking subtle swipes at the first-term senator over her leadership and ties to corporate interests.

“We could argue different ways about how to do it, but at the core, if you’re more likely to be meeting with the powerful than the powerless, you’re doing this job incorrectly,” he says in the video, which was released in English and Spanish. “I’m sorry that politicians have let you down, but I’m going to change that.”

A head-to-head matchup between Mr. Gallego and Ms. Sinema in the general election is likely to split the coalition of Democrats and independents who have powered Democratic victories in Arizona in recent elections. The divide could provide an opening for a Republican to retake a seat that has helped Democrats retain their narrow majority in the Senate.

Democrats in Arizona previously made motions that they intended to rally behind Ms. Sinema’s Democratic challenger. Mr. Gallego’s campaign team includes veterans from Senator Mark Kelly’s re-election bid in Arizona, as well as Democratic consultants who served on the successful 2022 Senate campaigns for Raphael Warnock in Georgia and John Fetterman in Pennsylvania. Mr. Gallego’s campaign also has taken on Chuck Rocha, a longtime Democratic strategist focused on mobilizing Latino voters.

Representative Greg Stanton, a Democrat who had also shown interest in running for the seat, said this month that now was “not the right time,” clearing the path for Mr. Gallego in the primary.

Among the Republicans weighing Senate runs are Kari Lake, the Trump-endorsed news anchor who last year lost her race for governor, and Blake Masters, who was defeated in a Senate race by Mr. Kelly.

For both Mr. Gallego and Ms. Sinema, the greatest factor will be the Republican nominee, said Mike Noble, a longtime nonpartisan pollster based in Phoenix.

A center-right candidate could consolidate Republican and right-leaning independent voters, most likely narrowing the chances for both Ms. Sinema and Mr. Gallego. A hard-right candidate like Ms. Lake or Mr. Masters, on the other hand, would most likely intensify the contest between Mr. Gallego and Ms. Sinema for moderates and the state’s large independent electorate, about one-third of voters.

“Heading into next year’s election, Kyrsten Sinema would like nothing else for Christmas than to have Kari Lake as the Republican nominee come 2024,” Mr. Noble said. “They both would love it.”

Ms. Sinema was elected to the Senate in a groundbreaking victory in 2018, in the first Democratic triumph since 1976 in a contest for an open Senate seat in Arizona. Her victory pointed to broader political shifts in the state. Once a longtime conservative bastion, Arizona has become a national battleground as the state’s Republican Party has veered further right, while growing numbers of Latino and independent voters have pushed the state to the center.

Ms. Sinema embraced solidly centrist positions in defeating her Republican opponent. Voter drives to register more Latinos, who generally vote Democratic in Arizona, also paid off for Ms. Sinema. But distaste for the senator has been growing among Latino activists and other parts of her Democratic base as she has positioned herself as a bulwark against major parts of her former party’s agenda, mainly attempts to increase taxes on corporate America and Wall Street.

National Democrats have been tight-lipped about their approach to the 2024 race, as some worry that a full-on offensive against Ms. Sinema in the general election might inadvertently help elect a Republican.

Mr. Gallego, who has been among Ms. Sinema’s fiercest critics, had been fielding input from his family over the holidays over whether he would run. He would be the first Latino senator from Arizona should he prevail.

In his campaign video released Monday, he describes his hard upbringing as one of four children raised by a single mother in Chicago. He made it to Harvard and worked to pay his way through school before enlisting in the Marine Corps. His combat experience on the front lines in Iraq, where he came under heavy fire and lost some of his closest friends, left him with post-traumatic stress disorder but also inspired him to go into public service, he said.

The ad positions Mr. Gallego as an advocate of strong government and a fighter for working-class families who he said “feel they are one or two paychecks away from going under.”

“The rich and the powerful, they don’t need more advocates,” he said. “It’s the people that are still trying to decide between groceries and utilities that need a fighter for them.”