TUCSON, Ariz. — Democratic Senate candidate Mark Kelly says he's voting for Joe Biden in the upcoming Arizona Presidential Preference election.

Kelly is running for the Democratic nomination for Senate in Arizona. He's hoping to challenge Republican Sen. Martha McSally in November.

"Joe Biden understands the challenges Arizonans face and knows what it’s like to be knocked down, get back up, and keep serving others," Kelly said in a tweet Monday. "We need a president who will unite us and find common ground to get things done. That’s why I’ll be voting for Joe Biden."

Joe Biden understands the challenges Arizonans face and knows what it’s like to be knocked down, get back up, and keep serving others. We need a president who will unite us and find common ground to get things done. That’s why I’ll be voting for Joe Biden. — Captain Mark Kelly (@CaptMarkKelly) March 2, 2020

Kelly's endorsement comes right before Super Tuesday, when Democrats in 14 states will cast their ballots in the presidential primary election. Arizona's presidential preference election is Tuesday March 17.

Earlier Monday, Democratic presidential candidates Pete Buttigieg and Amy Klobuchar recently dropped out and endorsed the former Vice President. It's widely seen as a move by the moderate candidates to blunt momentum from Vermont Sen. Bernie Sanders, who won three of the four states who have voted so far.

Biden finished with a resounding victory in South Carolina Saturday, besting his closest competitor -- Sanders -- by nearly 30 points. Sanders previously claimed a major victory in Nevada, and New Hampshire before that.