Arizona Republican John McCain will return to the Senate on Tuesday in time to participate in a procedural vote that could decide the future of the Affordable Care Act. In a statement released Monday night, McCain’s office said he “looks forward to returning to the United States Senate tomorrow to continue to working on important legislation, including health-care reform, the National Defense Authorization Act, and new sanctions on Russia, Iran, and North Korea.”

Earlier in the day, Senate Republicans held out hope that McCain would be cleared to travel from Arizona to Washington, D.C., following his recent brain-cancer diagnosis. “They were trying to get approval [from his doctors] for his travel arrangements,” Senate Majority Whip John Cornyn told Politico on Monday. He added: “I’ve personally volunteered to rent an RV.”

McCain’s presence at the vote is critical, given that the GOP needs 50 senators to agree to begin formal debate on health care, in what’s called a motion to proceed. McCain has told reporters he supports the legislative momentum to repeal Obamacare, but is unsure whether he will approve the final product. Last week, his office released a statement warning Congress not to “repeat the original mistakes that led to Obamacare’s failure”—namely, “that it was written on a strict party-line basis and driven through Congress without a single Republican vote.” Still, he’s largely expected to vote “yes” along with most of the GOP conference.