Sen. John McCain shook Republicans Friday by once again opposing a major bill aimed at overhauling Obamacare.

But the Arizona Republican signaled throughout the week that he would vote against the measure, stressing that his concerns about Republicans going around the Senate’s normal process, which he had voiced as he opposed another effort in late July, had not been fully addressed. Those concerns were enough for McCain to once again buck his party and go against his closest friend in the Senate, Lindsey Graham of South Carolina, who was a key sponsor of the new bill.