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.) has completed his first round of chemotherapy and radiation therapy to treat brain cancer, his daughter said Friday.

"My father completed first round radiation/chemo. His resilience & strength is incredible," Fox News host Meghan McCain tweeted. "Fight goes on, here's to small wins."

My father completed first round radiation/chemo. His resilience & strength is incredible. Fight goes on, here's to small wins. #fuckcancer — Meghan McCain (@MeghanMcCain) August 18, 2017

McCain, 80, was diagnosed last month with a glioblastoma, one of the most aggressive types of brain tumors, after a minor procedure to remove a blood clot above his left eye.

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Days later, the Arizona Republican returned to Washington as the Senate voted to begin debate on a Republican-led effort to repeal parts of the Affordable Care Act.

In a stunning vote last month, McCain joined two of his GOP Senate colleagues in rejecting a so-called "skinny" ObamaCare repeal, delivering a blow to his own party's efforts to undo former President Barack Obama Barack Hussein ObamaDemocratic Senate campaign arm outraises GOP by M in August A federal court may have declared immigration arrests unconstitutional Blunt says vote on Trump court nominee different than 2016 because White House, Senate in 'political agreement' MORE's signature healthcare law.

McCain returned to Arizona at the end of July to begin cancer treatment.