Sen. John McCain John Sidney McCainBiden's six best bets in 2016 Trump states Replacing Justice Ginsburg could depend on Arizona's next senator The Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy MORE (R-Ariz.), in dramatic fashion, emerged on the Senate floor Tuesday afternoon to a standing ovation from his colleagues to cast the deciding vote to begin the healthcare debate.

McCain walked onto the floor through the chamber’s East door as Republican and Democratic colleagues stood to applaud his return to work after being diagnosed with brain cancer last week.

The 80-year-old lawmaker, looking pale and with a wan smile, waved to his colleagues and touched his left breast, over his heart, to acknowledge them.

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He had a two- to three-inch scar over his left eye, where surgeons performed an emergency craniotomy over a week ago to remove a blood clot.

McCain then shook hands with Senate Republican Whip John Cornyn John CornynTumultuous court battle upends fight for Senate Texas Democrats roll out first wave of planned digital ads as Election Day nears Calls grow for Biden to expand election map in final sprint MORE (Texas) and Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellGraham: GOP will confirm Trump's Supreme Court nominee before the election Trump puts Supreme Court fight at center of Ohio rally The Memo: Dems face balancing act on SCOTUS fight MORE (R-Ky.) before casting a crucial vote to begin debate on House-passed legislation repealing and replacing major parts of ObamaCare.

Senate Democratic Leader Charles Schumer Chuck SchumerJacobin editor: Primarying Schumer would force him to fight Trump's SCOTUS nominee CNN's Toobin: Democrats are 'wimps' who won't 'have the guts' to add Supreme Court seats Republican senator says plans to confirm justice before election 'completely consistent with the precedent' MORE (N.Y.), who worked closely with McCain on immigration legislation, was so touched by the moment that he hugged McCain — even though Democrats staunchly oppose the GOP healthcare reform effort.

McCain cast the 49th vote to advance the measure and was immediately followed by Sen. Ron Johnson Ronald (Ron) Harold JohnsonThis week: Supreme Court fight over Ginsburg's seat upends Congress's agenda GOP set to release controversial Biden report Democrats fear Russia interference could spoil bid to retake Senate MORE (R-Wis.), who cast the 50th vote to begin the floor debate.

Two Republicans voted against the motion to proceed — Sens. Susan Collins Susan Margaret CollinsGraham: GOP will confirm Trump's Supreme Court nominee before the election Gardner signals support for taking up Supreme Court nominee this year Tumultuous court battle upends fight for Senate MORE (Maine) and Lisa Murkowski Lisa Ann MurkowskiGraham: GOP will confirm Trump's Supreme Court nominee before the election Gardner signals support for taking up Supreme Court nominee this year Tumultuous court battle upends fight for Senate MORE (Alaska) — so McCain’s vote was crucial.

Vice President Mike Pence Michael (Mike) Richard PenceGardner signals support for taking up Supreme Court nominee this year Biden leads Trump by 12 points among Catholic voters: poll GOP brushes back charges of hypocrisy in Supreme Court fight MORE voted to break a 50-50 tie and approve the motion.