Former astronaut Mark Kelly announces run for John McCain's seat in Arizona

Kelly will run against GOP Sen. Martha McSally.

Mark Kelly, a former Navy captain and retired astronaut who has become a strong advocate for gun control in the aftermath of a failed assassination attempt on his wife, former Rep. Gabby Giffords, announced a run for U.S. Senate in Arizona Tuesday.

Kelly announced his campaign for Senate in a video on Twitter.

"I learned a lot from being an astronaut, I learned a lot from being a pilot in the Navy, I learned a lot about solving problems from being an engineer. But what I learned from my wife is how you use policy to improve people's lives," he said.

He focused on access to affordable health care, the economy and climate change -- and though he didn't mention gun control, the presence of his wife, Giffords, carried a strong message about the role he has played in advocating for her and the issue.

"You remember when you entered Congress for the first time?" Kelly asked Giffords. "You know, I thought then that I had the risky job. Turned out that you were the one who had the risky job."

The couple, seated next to each other on a couch, finished the video with a famous quote passed through naval history about perseverance: "Damn the torpedoes, full speed ahead."