Sen. John McCain was Donald Trump's first head-scratching target in his bid for the White House. At a Republican presidential forum last July, then-long shot Trump dismissed McCain as "a hero because he was captured" in a Q&A with Frank Luntz, referring to McCain's six years as a prisoner of war in Vietnam.
Pundits and much of the public assumed Trump's White House hopes would be over before they had really begun. After all, who trashes POWs and the Republican Party's 2008 presidential nominee in one breath and lives to tell about it?
[Related: No Experience Necessary?] Eight months later, we have our answer. Trump now stands on the brink of winning the GOP nomination, while McCain is grinding through a dead-heat Senate race against Democratic Rep. Ann Kirkptrick , a three-term congresswoman and attorney.
No dynamic better embodies the internal conflict roiling the Republican Party today than the squeeze Trump is putting on McCain, the original independent and maverick of the party. On a larger scale, nobody has been a more consistent voice on American foreign policy for the GOP than McCain, whose views on conflict, diplomacy, and America's role in the world Trump has largely rejected.
In McCain's home state of Arizona, the latest Rocky Mountain Poll shows Kirkpatrick tied with McCain at 42 percent, with 16 percent of voters still undecided. But the same poll shows the biggest hurdle between McCain and a sixth Senate term may be the ticket he's running on, if Trump is at the top of it: Incredibly, Trump loses the red state to Hillary Clinton by seven points, just four years after Mitt Romney won the state by eight points for Republicans.
[Related: If You Can Fake It There, You'll Fake It Anywhere] Everything McCain has to do to win re-election is made more difficult by Donald Trump. He has to protect his left flank among women and Latinos, which made up 17 percent of the electorate in 2012 and are expected to be up to 21 to 22 percent of the vote in 2016.
But McCain also can't afford to ignore Trump and his supporters to his right. Not only does McCain have a primary to get through in August, he's losing an unusual share of Republicans, 27 percent, to Kirkpatrick, who is winning the state's rural vote at the moment.
McCain's answer to the Trump trap so far has been to put as much distance between him and the GOP front-runner as possible. He is skipping the Republican convention in July, eight years after headlining it himself, and he calls out Trump on policy differences when he can .
[Related: There's a Difference Between 'Rigged' and 'Corrupt'] McCain said POWs should get an apology from Trump for what he said in July (they didn't) and said Trump was wrong on every level when he called for torturing members of ISIS to get better intelligence out of them (Trump didn't back down).
But like nearly every other high-profile Republican in the country, McCain still says he'll support the GOP nominee, no matter who it is, even Donald Trump.
The Kirkpatrick campaign has seen the crack in that door and kicked it open with an ad we'll likely see replicated dozens of times in other races across the country. "Donald Trump is dangerous for America," the ad says . "But no matter what Donald Trump says, John McCain would support him for president."
The good news for McCain is that he remains very strong with the state's Hispanic population. He's winning the group by 13 points in the Rocky Mountain poll and layering his campaign with staff and messages to keep it that way. But the undecideds in Arizona include mostly independents, women and Hispanics, the three groups Trump bombs with again and again and again.
In a strange way, McCain was Trump before Trump was Trump. McCain was the original straight talker in his 2000 presidential run, regaling reporters on his Straight Talk Express bus by saying and doing everything a politician shouldn't if he wants to win a presidential nomination.
But while McCain hewed back to his party to win the nomination in 2008, Trump has done the opposite. The core message on his path to the Republican nomination has been the fact that the party establishment isn't the solution to Americans' problems; the establishment, including John McCain, is the problem.
The choices McCain makes to get to November will decide his fate in the Senate, but the choices Republican voters make will decide the future of the country itself.
Roll Call columnist Patricia Murphy covers national politics for The Daily Beast. Previously, she was the Capitol Hill bureau chief for Politics Daily and founder and editor of Citizen Jane Politics. Follow her on Twitter @1PatriciaMurphy Get breaking news alerts and more from Roll Call on your iPhone or your Android.