A former political opponent of Sen. John McCain John Sidney McCainMomentum growing among Republicans for Supreme Court vote before Election Day McConnell urges GOP senators to 'keep your powder dry' on Supreme Court vacancy McSally says current Senate should vote on Trump nominee MORE (R-Ariz.) urged him to step down from his office one day after he was diagnosed with brain cancer.

Kelli Ward — who lost to McCain last year in Arizona's Republican primary and is now running to challenge Sen. Jeff Flake Jeffrey (Jeff) Lane FlakeJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Republican former Michigan governor says he's voting for Biden Maybe they just don't like cowboys: The president is successful, some just don't like his style MORE (R-Ariz.) — said this week that "the medical reality of [McCain's] diagnosis is grim," and he should consider stepping down and having her take his place.

"Senator McCain has an aggressive brain cancer that is both devastating and debilitating. When the time comes that Senator McCain can no longer perform his duties in the Senate at full capacity, he owes it to the people of Arizona to step aside," Ward said in an interview with an Indiana radio station this week.

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Ward continued, saying that if McCain does leave office, Arizona Gov. Doug Ducey would be required to appoint a replacement senator to serve until the 2018 midterm election. When asked if her name was being considered as a replacement, Ward responded: "I certainly hope so."

"Because, you know, I have a proven track record from years in the state Senate of being extremely effective and of listening to the voice of the people that I represent,” she said.

Her comment came after McCain's office announced Wednesday that the 80-year-old senator had been diagnosed with an aggressive form of brain cancer.

McCain has said he will be back soon and thanked people for the outpouring of well-wishes he has received since the diagnosis.

Ward previously suggested in a Politico interview last year that McCain was likely to die in office and is too old for the job.

Ward has faced backlash following the comments this week, including Sen. Joe Manchin Joseph (Joe) ManchinNames to watch as Trump picks Ginsburg replacement on Supreme Court Momentum growing among Republicans for Supreme Court vote before Election Day Gardner on court vacancy: Country needs to mourn Ginsburg 'before the politics begin' MORE (D-W.Va.) who said she lacked integrity and honor.