Rep. Ruben Gallego (D-AZ) announced his long-awaited Senate candidacy for 2024 on Monday morning, putting him up against newly independent Sen. Kyrsten Sinema (AZ).

Gallego is a liberal former Marine combat veteran who has been "encouraged" by Democratic senators to run for Senate against Sinema. He announced his candidacy after being one of Sinema's harshest detractors, according to a report by Breitbart News.

After serving in the House of Representatives since 2015, he declared his campaign in a video in both English and Spanish, emphasizing his military service and his upbringing as a first-generation American with a single mother.

“The rich and the powerful, they don’t need more advocates,” Gallego said in the video, following a clip of him addressing veterans about his plans to run for Senate.

“It’s the people that are still trying to decide between groceries and utilities that need a fighter for them.”

The Challenger's Assault on Sinema

He also attacked Sinema in a statement, saying she has "abandoned Arizona" and has  “repeatedly broken her promises and fought for the interests of big pharma and Wall Street at our expense.”

In the weeks leading up to Gallego's announcement, sources indicated that the congressman had been recruiting and hiring the personnel needed to run against Sinema.

He also leads BOLD PAC, the political arm of the Congressional Hispanic Caucus, which will most certainly aid in his fundraising efforts.

Despite this, Sinema has yet to make an official declaration on whether she would run for reelection, as well as whether she will run in the Democratic primary or as a third-party candidate, which would result in a split ticket on election night, providing a strong Republican candidate an advantage.

She has, however, filed campaign documents with the Federal Election Commission (FEC) for the 2024 election cycle, citing her recent party switch to allow her committee to continue fundraising while she decides.

If Sinema competes in the Democratic primary, she may be able to run as a third-party candidate if she loses. However, standing as a third-party candidate has the potential to split the vote and assist a Republican win.

POLITICO's Take

Politico described one alternative last month that may allow the Arizona senator's party transfer to avoid a disputed Democrat primary but could result in a "horror scenario" for the party:

With three candidates on the ballot, a GOP nominee can capitalize on centrist and liberal divisions and win a Senate seat with a plurality vote. Democrats are not eager to intervene at the moment, but at some point they may have to make a call about whether to support Sinema, back whoever wins a primary or sit out the race altogether.

So, with a slim 51-seat majority, the Democrat Senatorial Campaign Committee (DSCC), the Senate Democrats' campaign arm, will not only have to try to keep the 51-seat majority, but will also potentially have to spend millions of dollars protecting Sinema, who has been a valuable asset for the left, in addition to some Democrat senators running in redder states in recent years.

Axios also stated that the results of the previous election cycle indicate that Arizona voters choose moderate candidates, which would ultimately benefit Sinema. Last election cycle, voters who did not deviate from "political standards" performed better. The state is also very evenly divided among Democratic, Republican, and independent voters.