Sen. John McCain John Sidney McCainBiden's six best bets in 2016 Trump states Replacing Justice Ginsburg could depend on Arizona's next senator The Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy MORE (R-Ariz.) is expected to return to the Senate next week after undergoing his first round of chemotherapy to treat brain cancer, his office confirmed Wednesday.

“Senator McCain will return to the U.S. Senate next week as Congress begins a new legislative session and looks forward to continuing his work for the people of Arizona and the nation," his office said in a statement.

McCain, chairman of the Senate Armed Services Committee, is set to manage the debate on the National Defense Authorization Act when he returns to the Senate, Politico reported.

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The Arizona lawmaker was diagnosed in July with a glioblastoma, one of the most aggressive types of brain tumors.

He completed his first round of chemotherapy and radiation therapy to treat brain cancer earlier this month.

McCain in recent weeks has been critical of some of President Trump's actions. Last week, the Arizona Republican criticized Trump over his pardon of former Maricopa County, Ariz., Sheriff Joe Arpaio.

In a statement at the time, McCain said Trump's decision to pardon Arpaio "undermines his claim for respect of rule of law as Mr. Arpaio has shown no remorse for his actions."

McCain also called it a "step in the wrong direction to force currently serving transgender individuals to leave the military."

McCain is also listed to appear at a Sept. 12 event at the Kennedy Center. The event includes a film screening, followed by a discussion with the filmmakers and McCain, among others.

Updated: 6:48 p.m.