Arizona Sen. John McCain will return to Washington this month after missing time in December to recover from an infection that arose from his cancer treatment, his friend Sen. Lindsey Graham predicted.

“Sen. McCain is in rehab. He’s coming back in January,” the South Carolina Republican said Sunday on CBS’ “Face the Nation” in response to a question about his GOP colleague’s health. “We need his voice now more than ever.”

McCain was diagnosed in July with glioblastoma, a powerful strain of brain cancer, after doctors discovered a tumor during surgery to remove a blood clot behind one of his eyes. He previously had three malignant melanomas, an aggressive form of skin cancer, removed in 1993, 2000 and 2002.

Graham’s comments, while vague on a specific timeline, track with statements previously made by Arizona Gov. Doug Ducey and Senate Majority Leader Mitch McConnell.

McCain’s doctors and office have remained publicly optimistic about the senator’s prognosis.

The senator is “responding positively to ongoing treatment,” Dr. Mark Gilbert, chief of neuro-oncology at the National Institutes of Health’s National Cancer Institute, said in a statement in December.

“He is grateful for the excellent care he continues to receive, and appreciates the outpouring of support from people all over the country. He looks forward to returning to Washington in January,” McCain’s office said last month.

The life expectancy for someone with glioblastoma is roughly a year.

Long considered a conservative foreign policy savant, McCain took to Twitter over the holidays to praise those protesting the government in Iran.

For too long, the Iranian people have been oppressed by their government, which cares more about sowing instability abroad than its own citizens. The U.S. stands with the brave protesters who yearn for freedom, peace, and an end to corruption in Iran. https://t.co/taDmyE1w7k

— John McCain (@SenJohnMcCain) December 30, 2017

He also used the social media platform to link to articles lambasting Chinese and Russian officials for suppressing democratic values.

McCain’s office has not issued a statement on his health in two weeks and could not immediately be reached for comment on this story at publication time.