Sen. John McCain, R-Az., sent a tweet Monday in which he provided an update on his health amid treatment for brain cancer.

Thanks to everyone for your support & words of encouragement! I'm feeling well & looking forward to returning to work after the holidays. — John McCain (@SenJohnMcCain) December 18, 2017

The senator had spent several days at Walter Reed National Military Medical Center in Maryland recovering from side effects of chemotherapy treatments.

McCain is spending the holidays with family and will be skipping the final vote on the Republican tax plan, which the House of Representatives is expected to take up on Tuesday, according to CBS News.

The underlying cancer is "responding positively to ongoing treatment," said Dr. Mark Gilbert, the doctor treating McCain at Walter Reed, in the CBS report.