More than two years ago, in May 2013, I followed Rand Paul to Iowa and New Hampshire. Just six months after Mitt Romney’s defeat in 2012, Paul had begun touring the country to lay the groundwork for his own presidential run—and for a new style of Republican politics.

I planned at the time to write about Paul’s ambition to be the man who could rescue the down-in-the-dumps Republican Party: an unorthodox politician who could break the GOP’s link to its toxic past by repudiating the neocon warmongering of George W. Bush, while forging a new connection with youth and minority voters by stressing civil liberties. Paul’s theory was that he could win the primary by building on the libertarian movement built by his father, the former Texas Representative Ron Paul, and reaching out to other Republican constituencies. And then, in a general election, he believed his views would have unique crossover appeal.

At that time, a lot of things seemed to be working in Paul’s favor. In March 2013, his 13-hour talking filibuster excoriating the Obama administration for its drone policy caused a sensation on the right. Various scandals in the news—subpoenas of reporters, the IRS scandal, the NSA’s cell-phone and email spying—seemed to underscore his crusade against government surveillance and intrusion. Conservative intellectuals were abuzz about the potential for a new brand of “libertarian populism” to excite voters who Romney hadn’t been able to inspire.

I never ended up writing the story, in part because of the frustration of dealing with Paul’s disastrous communications staff, but largely because I lost faith in the premise. In both Iowa and New Hampshire, the limits of Paul’s pitch were obvious. I saw firsthand that what he was trying to pull off—remaking the GOP in his image—was going to be a lot harder than he assumed.

In Iowa, Paul held a press conference with a group of evangelical pastors and packed a GOP dinner in Cedar Rapids with a youthful, enthusiastic crowd. But when he devoted part of his speech to advocating immigration reform—“I am in favor of immigration reform,” he said. “If you want to work in this country, I’m in favor of finding a place for you to work”—the room went silent. (The following month, Paul would cast a vote against the comprehensive immigration-reform bill that passed the Senate.)

In New Hampshire, Paul and Reince Priebus, the Republican National Committee chairman, met privately with a group of state GOP officials and liberty-movement activists—an attempt to mend the distrustful relationship between the two groups. Ron Paul supporters in a few states had taken over Republican delegations and staged a walkout from the 2012 convention; Rand Paul’s promise was that he could bring them back into the party fold. At that night’s GOP dinner, where Priebus and Paul were to give back-to-back speeches, vendors were selling T-shirts with the slogan “The Palatable Paul.” I chatted at the bar with a local GOP official who had come to regret his support for the war in Iraq.

Priebus devoted a section of his speech to blasting the attorney general at the time. “Let’s not forget it was Eric Holder reading the Miranda rights to the Christmas Day bomber,” he said angrily. “It was Eric Holder that said that he would read the legal rights to the dead body of Osama bin Laden. He said that it would be his living legacy to try the 9/11 terrorists in civilian courts.”

Speaking next, Paul told a story that seemed like an implicit rebuttal of Priebus. He had recently met a policeman who helped people at the scene of the Boston bombing, he said. “He had the same thought every one of us would have—anger, wanting to punish these people,” Paul said. “It’s human. It’s normal. But he said, ‘What separates us from them is that when we did finally capture him, we sent the suspect to a hospital. He’s going to be tried in a court of law. He’s going to have an attorney.’ It’s our Bill of Rights, it’s our law, it’s going through the process that makes us different from them.”

Again, there was no applause, and Paul moved on to telling jokes about Obamacare.

This was the basic problem that Paul’s presidential campaign never managed to solve: He was trying to perform a personality transplant on the Republican Party, and political parties just aren’t that easy to change.

There were other problems. Paul wasn’t the deftest politician—he was positively outgoing compared to his father, but he still seemed like a basically inward-focused person more engaged with ideas than with other humans. In Cedar Rapids, I watched him try to make small talk about infrastructure with a man who owned an asphalt company. Paul ran out of questions and stared at his shoes for a long moment. “Uh, that’s probably enough shop talk,” the man said, then quickly walked Paul into the house where he was holding a meet-and-greet. Paul tended to snap at the media for perfectly legitimate questions about things like the fact that his ghostwriter turned out to be a neo-Confederate, or that his speeches were often pastiches of unattributed passages from news articles and think-tank reports.

Paul’s campaign also had issues. As McKay Coppins reported in his book The Wilderness, his advisers were deeply divided on strategy: One camp believed he could win over Chamber of Commerce Republicans and big-money donors by stressing his fiscal conservatism, while another group thought he should focus on conservative Christians by stressing his status as a fellow grassroots outsider. The latter camp won out, and the strategy proved dubious in practice. The ragtag college crowd of goldbug stoners that Ron Paul had attracted didn’t appreciate Rand Paul’s feints to the middle; the evangelicals were vulnerable to appeals from a candidate who spoke their language more fluently, like Ted Cruz; and the donor class was unimpressed by a candidate they viewed as amateurish. Paul failed to get support from either Peter Thiel, the Silicon Valley magnate who’d contributed large sums to Ron Paul’s campaign, or the Koch brothers, whose philosophy closely mirrored his own.

With the rise of the Islamic State and the terror attacks in Paris and San Bernardino, Paul’s dovish message seemed increasingly unsuited to his party’s mood. His father had finished third in Iowa and second in New Hampshire, getting more than 20 percent of the vote in both places; Rand Paul got less than 5 percent of Iowa caucus-goers on Monday, and was polling at just 3 percent in New Hampshire. Cruz has been openly angling for the libertarian vote: At his New Hampshire stops, he screens a video, “Liberty Leaders for Cruz,” that features testimonials from former Paul supporters.

Rand Paul, meanwhile, faces a challenge back home from a well-credentialed and potentially well-funded Democratic Senate candidate. And so his presidential ambitions have come to an end, leaving his friends and supporters to wonder what might have been. As one Republican consultant who's close to Paul, and said that he'd like anonymity so that he could speak candidly, told me on Wednesday: “Hindsight is 20/20. But Rand is an ophthalmologist.”

2016 Distilled