Retired astronaut Mark Kelly kicked off his Arizona Senate bid on Saturday with a rally in Tucson, dubbing his campaign "a mission to lift up hardworking Arizonans."

Kelly, a former Navy pilot and astronaut who became a vocal advocate for gun control after his wife, former Rep. Gabrielle Giffords (D), nearly died in a shooting in Tucson in 2011, announced this month that he will mount a challenge to incumbent 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-Ariz).

The Democrat on Saturday called his campaign “a mission to lift up hardworking Arizonans, make Arizona safe and secure, give every family in this state access to affordable health care and grow wages for our middle class.”

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Several hundred supporters came to hear Kelly, The Associated Press reported. He invoked the 2011 shooting as a life-changing moment for both him and Giffords, who introduced him at the rally Saturday.

“The shooting changed both of our lives — dramatically, negatively and permanently,” Kelly said. “Like so many families, we were knocked to the ground in a drastic and unexpected way. But we got up.”

“We need bold solutions. Courageous ideas. Leaders who put people first, not politics,” Giffords echoed. “I know the perfect person for the job.”

Kelly cast himself as a moderate in his speech, listing climate change, immigration and gun control as areas on which he would focus.

“If we continue to stay so focused on partisanship and partisan politics in this country, we’re going to have a hard time solving our biggest problems,” he said.

Kelly may face a primary challenge for the Democratic Senate nomination in Arizona, as 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), who is based in Phoenix and has strong ties to grass-roots activists, is also considering a run.

Democrats are hopeful that Kelly could put up a strong showing in a state that has been trending left in recent years, electing former Rep. Kyrsten Sinema in November as its first Democratic senator since 1988.

McSally was appointed to her Senate seat late last year following the death of longtime 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 (R). Next year's electoral contest will determine who fills the Senate seat for the final two years of the term.