The moves failed to appease McCain's conservative critics then, and those critics are livid over what has happened since. McCain, who played an integral role in the Senate's bipartisan "Gang of 8" immigration bill in 2013, was back down to a 49 percent on Heritage Action's scorecard during the 113th Congress. In the first five months of 2015, he has already risen back up to 73 percent.
In May, the McCain campaign tweeted news that he'd received a 91 percent rating from the American Conservatives Union "for fighting for conservative ideas & values." The ACU quickly responded to assert that while the number was accurate, he'd received a 52 percent rating on their scorecard in 2013, and was not considered an ally.
Now, it appears McCain's run will be defined largely by two questions: Can he again garner enough support on the Right to head off a primary challenger? And if he makes the moves needed to get that support, can Kirkpatrick cross far enough into the political middle to make him pay for it later?
For their part, the Far-Right groups that failed to unseat McCain in 2010 say they're ready to jump in again if a strong candidate like Salmon emerges. Sources say Salmon is considering the race seriously, though he hasn't commented on such a move. Conservative activists say that if they have a candidate, the rise of voting scorecards and rapid-response technology has made them much more prepared than ever to hold the senator accountable on his votes over the past six years.
Democrats, meanwhile, are touting Kirkpatrick as the first general-election challenger McCain has faced who can raise enough money to effectively highlight McCain's rightward shift. McCain, said Goddard, has "run right in the primaries and never been held accountable for it, either because his opponent didn't have the wherewithal or just didn't use the issues presented. It's no question she's his toughest challenger.... If Ann can hold him accountable if he swings far right—if she can make him stay there—that would be very harmful to him."
(Kirkpatrick may still face a primary of her own. A Supreme Court decision expected to come down any day could compel redistricting that affects other members of her delegation, most notably Rep. Kyrsten Sinema, who has not ruled out the Senate race.)
McCain's allies concede that if he were to face sitting members of Congress in both races, it's "unquestionable" that this would be his toughest reelection yet. But even a tougher race than usual doesn't mean that the iconic war hero and chairman of the Senate Armed Services Committee is in real danger.
And recent history suggests that Arizona remains a solidly red state, even in presidential years. In 2012, Democratic Senate nominee Richard Carmona lost, 46 percent to 49 percent, to then-Rep. Jeff Flake. (The two were racing for the state's open Senate seat vacated by retiring Republican Sen. Jon Kyl.) And in 2014, none of the Republican incumbents succumbed to challenges from the Right, and none went on to lose in November.