By JOE WILLIAMS and JOHN M. DONNELLYUpdated 10:10 p.m. | Sen. John McCain will return to the Senate chamber Tuesday in time for a key procedural vote on the Republican legislation to repeal and replace the 2010 health care law, his office confirmed Monday evening.

The Arizona Republican announced last week he was diagnosed with glioblastoma, an often fatal form of brain cancer.

The news is a boost to the GOP effort to overhaul the U.S. health insurance system. Senate Majority Leader Mitch McConnell needs the support of at least 50 of the 52 Republican members to vote on the motion to proceed to the House-passed repeal-and-replace bill in order to bring up a Senate version for consideration.

Senators said Monday night they still did not know which version they would be debating.

The return of McCain, whose vote is expected to help Republicans clear the procedural hurdle, increases McConnell’s odds for success.

McCain previously expressed concern with the most recent GOP health care bill.

“One of the major problems with Obamacare was that it was written on a strict party-line basis and driven through Congress without a single Republican vote,” he said. “Congress must now return to regular order, hold hearings, receive input from members of both parties, and heed the recommendations of our nation’s governors so that we can produce a bill that finally provides Americans with access to quality and affordable health care.”

It is unclear whether several swing votes on health care, such as Sens. Lisa Murkowski of Alaska, Dean Heller of Nevada and Shelley Moore Capito of West Virginia, will support the motion to proceed.

“Senator McCain looks forward to returning to the United States Senate tomorrow to continue working on important legislation, including health care reform, the National Defense Authorization Act, and new sanctions on Russia, Iran and North Korea,” McCain’s office said in a statement.

Defense authorization

McCain, the Armed Services Committee chairman, plans to helm the Senate’s debate on its fiscal 2018 Pentagon policy bill and potentially play an active role in the sanctions legislation.

McConnell offered a motion to proceed to the defense authorization bill Monday evening, putting it in the queue for likely consideration before the summer recess.

The House is slated to pass the sanctions bill on Tuesday. House and Senate negotiators announced over the weekend they had reached agreement on several changes to Senate-passed legislation that resulted in a new bill introduced in the House containing sanctions targeting Russia, Iran and North Korea.

Rachel Oswald contributed to this report.