Story highlights Republicans are hoping to pass an Obamacare repeal in Graham-Cassidy bill

Sen. Lindsey Graham's best friend John McCain could stand in the way (again)

Washington (CNN) Sen. John McCain bucked his party -- and his President -- in the most extraordinary fashion this summer.

Not even two months later, the Arizona Republican finds himself confronting perhaps an even tougher dilemma: The possibility of once again defying his GOP colleagues, including his closest friend on Capitol Hill, and casting another potentially decisive vote that prevents Republicans from achieving their years-long campaign pledge to repeal Obamacare.

McCain's dramatic "no" vote in July -- along with opposition from Sens. Lisa Murkowski of Alaska and Susan Collins of Maine -- killed a Senate Republican bill to repeal Obamacare. At the time, the veteran senator made an impassioned speech on the Senate floor, pleading with his colleague to return to doing business through "regular order" -- holding hearings and working with Democrats across the aisle.

"Let's trust each other," McCain said. "Let's return to regular order. We've been spinning our wheels on too many important issues because we keep trying to find a way to win without help from across the aisle."

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