The Dems lobbied McCain while in recovery, and he agreed to support the Democrat cause.

According to The Hill,  McCain was lobbied by the Dems and agreed to block the GOP repeal bill.  Time for McCain to be ridden out of town.  

Look,  the truth of the matter is this,  the GOP does not have 52 Republican Senators.  It only has 50,  make that 49 if you count Susan Collins  (which I do not  -  she is a liberal, yes,  but from Maine. She does not pretend).  Murkowsky and McCain are,  in fact, pretenders of the first order.
Former Vice President Joe Biden reportedly called Sen. John McCain (R-Ariz.) ahead of Friday's vote on Senate Republicans' healthcare bill, asking that he oppose the legislation. 
According to a report by The Washington Post, McCain was called by both Biden and former Sen. Joe Lieberman (I-Conn.) ahead of the vote, both pleading with McCain to oppose the "skinny' repeal.