Probably not. But if he does, the odds of a Democratic senate in 2017 will go up by about 15%.
To many conservatives, libertarians, conservatarians, tea partiers, and general wacko-birds (as McCain calls us), McCain wouldn't be much better than a Democrat.
Look at the Republican polls: Trump's doing great, and Carson and Cruz are also picking up steam. You've got a guy who basically called the Senate Majority leader, of his own party, a liar to his face, a guy who has never, ever even ran for elected office, ever, and doesn't even have business or military experience, and a guy who insults basically everyone and their mother--that's your top 3 in Iowa, and 3 of the top candidates overall. The other two candidates trending upward are someone who hasn't held elected office--Fiorina's not as anti-establishment as those 3 I named, but an outsider nonetheless, and a moderate Governor--not an outsider like the other 4, but Kasich's rise is an indicator of how weak the anointed establishment candidate (Jeb!) is.
All in all, it's clear the voters are mad as hell, and want something different. This is a revolution within the party, a peasant's uprising of sorts, but instead of violence they're attacking with Trump, Carson, Cruz, to a lesser extent Fiorina, and even some of the bourgeois, to continue the analogy, are trying a regime change as well--via a soothing, harmless midwesterner.
The point: conservative voters don't give a damn whether McCain, or any other moderate Republicans, win or lose against Democrats in the general election. The grassroots of the party want to see people who agree with them, like Kelli Ward, get elected over the establishment who continually disappoints them by being consistently crap.
Normal Republican vs. Democrat analysis doesn't apply as much this time around--it's Republican Establishment vs. Conservative/Tea Party/Grassroots as much as it is Republican vs. Democrat. You've got a similar thing going on across the aisle with Bernie Sanders, but the Democrats have been less crap so their grassroots hates their establishment a little less.
Poll
