John McCain’s political future remains uncertain.

The 81-year-old Republican Senator checked into Maryland’s Walter Reed National Military Medical Center on Wednesday after experiencing “normal side effects” of his cancer treatment, CBS News reports.

McCain’s office released a statement saying the Arizona lawmaker planned to be “returning to work as soon as possible.”

“Senator McCain is currently receiving treatment at Walter Reed Medical Center for normal side effects of his ongoing cancer therapy. As ever, he remains grateful to his physicians for their excellent care, and his friends and supporters for their encouragement and good wishes. Senator McCain looks forward to returning to work as soon as possible.”

In July, McCain was diagnosed with glioblastoma, an aggressive form of brain cancer. The diagnosis came after he received a craniotomy to remove a blood clot above his eye. McCain has since completed his first round of chemotherapy treatment.

The former presidential candidate told Lesley Stahl of “60 Minutes” in September:

“They said that the prognosis is very, very serious. Some say 3 percent, some say 14 percent. You know, it’s — it’s a very poor prognosis. So I just said, ‘I understand. Now we’re going to do what we can, get the best doctors we can find and do the best we can.’ And at the same time celebrate with gratitude a life well lived.”

McCain’s daughter, Meghan, who co-hosts ABC’s “The View,” shed tears on Wednesday while interviewing former Vice President Joe Biden, whose son, Beau, lost his life to glioblastoma in 2015.

In an emotional moment, Joe Biden consoles Meghan McCain, whose father was diagnosed with the same cancer as Biden’s late son Beau: “There is hope. And if anybody can make it, your dad [can].” pic.twitter.com/5IyS0qAgws — The View (@TheView) December 13, 2017

Biden gave Meghan McCain words of comfort, saying “There’s a lot of things happening. There’s breakthroughs occurring now … It could happen.”

McCain’s hospitalization caused him to miss votes and the signing of a defense policy bill this week.

The Senator’s absence raised the question about whether he will be back in time to vote on the Republican tax reform bill. His office’s statement that “Senator McCain looks forward to returning to work as soon as possible” seemed to suggest that he would make it for the vote. But McCain himself is yet to confirm.