(CNN) M.J. Hegar, a Democrat and former Air Force helicopter pilot who nearly beat a Republican congressman in a conservative district in 2018, announced a campaign Tuesday to take on three-term Sen. John Cornyn of Texas.

"Unseating an entrenched incumbent senator is going to be tough, but I've faced worse odds in my life," tweeted Hegar. "Saddle up, Texas. I'm in."

She released a video that pointed to her viral ad from the 2018 campaign to represent a congressional district north of Austin, Texas. The ad recalls how she won her Purple Heart during her third tour in Afghanistan, after she was shot, her chopper went down and she returned fire on the Taliban.

Unseating an entrenched incumbent senator is going to be tough, but I've faced worse odds in my life. Saddle up, Texas. I'm in. Join me at https://t.co/cDULHGNQXG https://t.co/Xbt0oB4xYD — MJ Hegar (@mjhegar) April 23, 2019

Hegar lost her race by a few points to incumbent GOP Rep. John Carter, but she claims in her new ad that her campaign helped changed the "status quo" in Texas politics.

Texas last elected a Democrat to the US Senate in 1988. For years, Democrats have hoped that the state's changing demographics and candidates with compelling personal stories could overcome the state's Republican affiliation. In 2018, then-Rep. Beto O'Rourke captured liberals' imaginations but narrowly lost to Sen. Ted Cruz in the most expensive Senate fight ever.

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