The U.S. Senate special election pitting Republican incumbent Martha McSally against Democrat Mark Kelly is "key to keep the Senate majority" for the GOP next year, McSally told "Fox & Friends" Tuesday.

“People have known Arizona is key for the presidential race ..." McSally said. "Now we’re key to ensure that the Supreme Court nominee goes through and that we’re able to shift the court for generations to come."

ANDY MCCARTHY EXPLAINS WHY ARIZONA SENATE ELECTION COULD MAKE OR BREAK TRUMP SCOTUS PICK

McSally and Kelly, a former astronaut, are battling for the seat formerly held by the late Sen. John McCain, who was reelected in 2016. After McCain died of brain cancer in August 2018, former Sen. John Kyl served out the remainder of that year. Arizona Republican Gov. Doug Ducey then appointed McSally to fill the seat at the beginning of 2019.

Under Arizona law, Kelly could be sworn in as soon as Nov. 30 if he defeats McSally Nov. 3, reducing the Republican majority by one in the Senate's lame duck session.

The latest RealClearPolitics polling average shows Kelly leading McSally by 6.7 percentage points, but the retired Air Force fighter pilot says she will not lose the seat without a fight.

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“I lost my dad when I was a kid ... It propelled me on a path of service and fighting for the vulnerable and fighting for others and we’re down to the wire here,” McSally said.

“Now, I’m standing on the wall to make sure the radical left does not take over our country and I am standing there to make sure that Chuck Schumer is not in charge in the Senate, and people want a fighter. We care about our freedoms in Arizona, so it is very much resonating.”

Fox News' Marisa Schultz contributed to this report.