McCain will return to Senate next week following treatment in Arizona: 'This country needs my father now more than ever,' says daughter

The Arizona Republican has been undergoing treatment for brain cancer.

"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," the Republican lawmaker's office said in a statement Wednesday.

McCain, the chairman of the Senate Armed Services Committee, is expected to lead debate on a defense policy bill.

Following the announcement of McCain's return, daughter Meghan tweeted, "This country needs my father now more than ever."

McCain celebrated his 81st birthday on Tuesday, tweeting, "Thank you for all the birthday messages! It's been wonderful celebrating with family in #Arizona doing the things we love most."

On Aug. 18, Meghan announced that her father completed his first round of treatment, tweeting, "My father completed first round radiation/chemo. His resilience & strength is incredible. Fight goes on, here's to small wins." Later that day, McCain tweeted a photo with the staff at the Mayo Clinic.