(Recasts; adds details and background on Senate healthcare vote)
WASHINGTON, July 15 (Reuters) - U.S. Senator John McCain will remain in Arizona next week to recover from surgery, just as the Senate prepares for a crucial vote on healthcare legislation that could hinge on a single "no" vote.
McCain had a procedure that removed a 2-inch (5-cm) blood clot above his left eye, his office announced in a statement on Saturday. "On the advice of his doctors, Senator McCain will be recovering in Arizona next week," it said.
It was unclear how McCain's absence might affect Senate Republican plans to vote next week on legislation to dismantle and replace Obamacare. Senate Republican leader Mitch McConnell needs 50 "yes" votes for passage in a chamber that the Republicans control by a 52-48 margin.
Repealing and replacing President Barack Obama's signature healthcare law was a top campaign promise for President Donald Trump and Republicans in Congress. But two Republican senators have already declared their opposition to revised legislation that was unveiled on Thursday.
McCain, the 2008 Republican presidential nominee, was resting comfortably at home in good condition after the Friday operation, his office said.
McCain has expressed concern about the healthcare bill but has not said how he would vote.
Senate Republican leader Mitch McConnell's office did not immediately respond to a request for comment on how the healthcare vote might be affected.
McCain's surgeons removed the clot during a minimally invasive craniotomy through an incision in the 80-year-old lawmaker's eyebrow. Tissue pathology reports would be available within the next several days.
"Thanks to zMayoClinic for its excellent care -- I appreciate your support & look forward to getting back to work!," McCain, who chairs the Senate Armed Services Committee, said in a tweet late on Saturday. (Reporting by David Morgan; Editing by Cynthia Osterman)