Retired astronaut Mark Kelly on Tuesday said he will run for a Senate seat in his adopted home state of Arizona, giving Democrats an early chance at a seat they have not held since the late Sen. Carl Hayden (D) retired in 1969.

Kelly spent more than 54 days in space across three NASA missions. He has turned to politics in the years since his wife, former Rep. Gabrielle Giffords (D), survived an assassination attempt in a 2011 mass shooting that claimed the lives of six others.

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Announcing his campaign in a video posted to Twitter, Kelly leaned hard into his career as a Navy aviator and astronaut — and on his wife, who appeared with him.

“It becomes pretty obvious pretty early when you get into space that we’re all in this together,” Kelly said in the video.

Kelly will face another former aviator, Sen. Martha McSally Martha Elizabeth McSallyTumultuous court battle upends fight for Senate Grassley, Ernst pledge to 'evaluate' Trump's Supreme Court nominee The Hill's Campaign Report: Biden goes on offense MORE (R), who held the same seat in Congress that Giffords once held.

McSally was appointed to fill the remainder of the late Sen. John McCain John Sidney McCainCindy McCain endorses Biden: He's only candidate 'who stands up for our values' Biden says Cindy McCain will endorse him Biden's six best bets in 2016 Trump states MORE’s (R) term after McCain’s first replacement, Jon Kyl, stepped down at the end of last year. McSally had run for an open Senate seat last year, losing narrowly to Sen. Kyrsten Sinema (D).

Kelly’s interest in running for the seat was a poorly guarded secret. He met with Senate Minority Leader Charles Schumer Chuck SchumerSenate Democrats introduce legislation to probe politicization of pandemic response Schumer interrupted during live briefing by heckler: 'Stop lying to the people' Jacobin editor: Primarying Schumer would force him to fight Trump's SCOTUS nominee MORE (D-N.Y.) and Democratic Senatorial Campaign Committee Chairwoman Catherine Cortez Masto Catherine Marie Cortez MastoDemocratic Senate campaign arm raised nearly M in August VA problems raise worries about mail slowdown, prescriptions Cortez Masto touts mail-in voting in convention speech MORE (D-Nev.) earlier this year to discuss the race, and he had identified a campaign manager by last month, sources told The Hill.

He has been working with Rodd McLeod, a veteran Arizona Democratic strategist who worked on Giffords’s first race.

The Arizona Democrat said Tuesday he would work to ensure affordable health care and wage growth, standard Democratic talking points. But he struck a tone similar to Sinema, who ran her 2018 campaign by tacking more toward the middle of the ideological spectrum than toward the left.

“Partisanship and polarization and gerrymandering and corporate money have ruined our politics, and it’s divided us,” Kelly said. “We’ve seen this retreat from science and data and facts, and if we don’t take these issues seriously, we can’t solve these problems.”

Arizona and national Democrats see Kelly as their ideal candidate against McSally in a state that has moved left in recent years. No Democrat has won Arizona’s presidential electoral votes since Bill Clinton William (Bill) Jefferson ClintonChelsea Clinton: Trump isn't building public confidence in a vaccine Hillary Clinton launching podcast this month GOP brushes back charges of hypocrisy in Supreme Court fight MORE in 1996, but Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE came within 3.5 points of winning there in 2016.

Sinema became the first Democrat to win a Senate seat in Arizona since Dennis DeConcini in 1988, and Democrats now hold five of the state’s nine congressional districts.

Kelly may not have the race all to himself. Rep. Ruben Gallego Ruben GallegoHispanic caucus report takes stock of accomplishments with eye toward 2021 Senators call on Pentagon to reinstate funding for Stars and Stripes newspaper Hispanic Caucus campaign chief to mount leadership bid MORE (D) is considering a bid as well. Another potential candidate, former Attorney General Grant Woods — a Republican-turned-Democrat who served as McCain’s first congressional chief of staff — said earlier this week he would not run.

Updated at 9:02 a.m.