As a strategic matter, Walker may have chosen the wrong lane, or segment of the electorate. Correctly sensing conservatives’ desire for anti-establishment candidates, he tacked hard to the right, renouncing his previously moderate positions on immigration and emphasizing his social conservatism. In his blue state, Walker was used to being the most conservative guy in the room. But on the national stage, in a party tilting ever rightward, there was always someone willing to go farther, and many conservatives suspected him of posturing. When Donald Trump’s candidacy began to take off, Walker’s support in Iowa quickly evaporated. In the words of the Republican consultant Liz Mair, who had worked for Walker’s Wisconsin campaigns but was fired from his presidential effort for a handful of impolitic tweets, Walker failed because he became “so invested in winning, no matter what it took, that he lost sight of his real identity as a political leader.”

The practical effect of Walker’s hubris was a campaign that spent too much money too fast, on the assumption that its early flood of support would continue unabated. When the wheels began to come off and donors got skittish, there were too many mouths to feed. The super PAC supporting Walker was still flush with cash—two weeks ago, it reserved $7 million worth of television airtime in Iowa—but the actual campaign was broke. “People don’t stop running for president because they run out of ideas or run out of desire to keep giving speeches,” Terry Sullivan, campaign manager for Marco Rubio, said on Monday. “They stop because they run out of money.”

Last week’s Republican debate was the final straw.