McCain's professed independent streak is supported by these data. About 75 to 85% of the time, McCain voted with his party's majority. More frequently than the average Republican, however, McCain voted with the Democratic majority rather than the Republican majority on votes that put the two parties on opposite sides.There is the statistical evidence that McCain is more likely to reach across the aisle to work with the Democrats than Obama or Biden would to work with Republicans. That is why the claims that Obama has made to be a post-partisan politician who would heal the divisions in Washington just isn't all that credible.
Obama and Biden, on the other hand, have both been more likely than the typical Democratic senator to vote with the Democratic party position. In each of his three full years, Obama voted over 95% of the time with the Democratic majority on party votes. McCain reached 90% only once, in 2007.Biden's party support level has hovered between about 90 to 95%. From these data, McCain can more credibly make the claim that he is willing to buck his party. He has voted against his party majority about 15 to 25% of the time across the Bush years, compared to about 3% for Obama and 5 to 10% for Biden.
Of course, it is that maverick quality of John McCain's that drives conservatives nuts. It was quite ironic to see that convention hall of Republican activists cheering Joe Lieberman as he praised McCain's efforts to thwart Republican ideas by working with the Democrats. I bet few of those party officials were actually thrilled at the time when McCain was working together with Senators Feingold on campaign finance reform or Ted Kennedy on immigration. It shows how dismal the standard Republican brand now is that the party faithful are cheering and applauding the tales of McCain supporting efforts that many Republicans disagreed with in the first place.
If McCain does win, those same activists may come to regret putting in office someone with a history of supporting Democratic initiatives. Their only consolation is that the alternative was a lot worse.