I don't trust McCain no matter what he says. He could be laying a setup. We all know that McCain has a visceral hate for Trump and the Republican base that elected him. At the last minute McCain will say that he 'had' to vote against it, because of this detail or that detail, or this thing or that thing.
Then he will run over to Schumer/CNN/Pelosi for his earned high-five, just like he did last time.