Sen. John McCain completed his first round of chemotherapy and radiation treatment for aggressive brain cancer, his daughter Meghan tweeted Friday.

The Arizona Republican was diagnosed with a brain tumor last month soon after having surgery to remove a blood clot above his eye.

He returned to Washington late last month to cast the deciding vote against repealing Obamacare. He has since returned to Arizona for cancer treatment.

Meghan McCain tweeted Friday that the Arizona senator's "resilience & strength is incredible."

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

"Fight goes on, here's to small wins," she tweeted.