I stood backstage at a rally in Minnesota in October 2008 where Senator McCain took the microphone from a woman in the crowd who spoke about her fears, including that Barack Obama was “an Arab.” Senator McCain said, “No, ma’am,” and explained that Mr. Obama was a good and decent family man and an American with whom he simply disagreed on policy matters. This interaction will go down as one of the finest moments from one of the country’s finest men. But it was also an early warning that the Republican base was profoundly agitated.

To some in the news media, voter anger seems like a new phenomenon. But they attended the same Palin rallies I did — we all should have seen this coming. The Alaska governor whipped the crowds into a frenzy with her fiery attacks on the media and the establishment politicians that she had gleefully upended in the Alaska statehouse. When her rallygoers shouted crude comments from the stands, as the woman at the Minnesota rally had done, there was no confrontation between Ms. Palin and the offender. When the press started to report on the angry rhetoric coming from those Palin crowds, I remember Senator McCain’s concern. The growing furor in the Republican Party was something that we, as a campaign, failed to address, but to the crowds, Sarah Palin proved the more satisfying politician on the ticket because of it.

Ms. Palin owned the resentment voters in the Republican Party. They became her cause. And when the campaign concluded, she became the poster politician for the Tea Party movement. She was its first star, and hers became a coveted endorsement. Ms. Palin typically picks candidates who are trying to unseat incumbents and more experienced politicians, an ironic development considering that she was selected as a running mate to reinforce Mr. McCain’s brand as a “maverick” — but a maverick who worked within the Senate and the Republican Party.

She has now turned the institutions in which he has proudly served into liabilities for the candidates running against her mama-grizzly-approved outsiders. The party bears some responsibility for her success. Our base has grown increasingly exasperated with Washington Republicans who, despite historic victories in the midterm elections of 2010 and 2014, seem incapable of reversing President Obama’s legislative agenda or asserting themselves in the country’s foreign policy debates.