Back in 2014, Matt Yglesias predicted that Mike Pence would be the Republican Party’s 2016 presidential nominee.

When I first heard the pitch, I was dismissive. But Matt’s case was convincing. Pence, he argued, was "generic Republican" come to life. He was like every other Republican, but a bit more so, and a bit better liked. In the House, he led the conservative Republican Study Committee and then was elected to GOP leadership. As governor of Indiana, his fellow Republican governors named him to the Executive Committee of the Republican Governors Association. As Politico’s Mike Allen wrote, Pence could "bridge the establishment/business and evangelical/tea party wings of the GOP."

So that was the case for Pence: He was a generic, predictable conservative who was broadly liked by his colleagues and by the party’s major interest groups. And that was what Republicans would want, right?

Wrong.

Donald Trump is neither generic nor particularly Republican, and his whole campaign was built on the idea that even Republicans didn’t want another generic Republican. So he made his eccentricities, his heterodoxies, and his independence from the party’s interest groups and leading politicians a selling point. Trumpism was something distinct from Republicanism: a potent form of white nationalism mixed with a bit of economic populism, a loathing of the Washington establishment, and a charismatic celebrity.

But Trumpism is losing to Republicanism. In choosing Pence, Trump is selecting a vice president who undermines everything that was distinct about his campaign.

I am pleased to announce that I have chosen Governor Mike Pence as my Vice Presidential running mate. News conference tomorrow at 11:00 A.M. — Donald J. Trump (@realDonaldTrump) July 15, 2016

Trump has made much of his opposition to the Trans-Pacific Partnership deal. "The TPP would be the death blow for American manufacturing," he said.

Pence doesn’t agree. "Trade means jobs, but trade also means security," he tweeted. "The time has come for all of us to urge the swift adoption of the Trans Pacific Partnership."

Trade means jobs, but trade also means security. The time has come for all of us to urge the swift adoption of the Trans Pacific Partnership — Governor Mike Pence (@GovPenceIN) September 8, 2014

Trump sets himself apart from his fellow Republicans by promising to oppose cuts to Social Security and Medicare. "I’m not going to cut it," he said of Social Security, "and I’m not going to raise ages, and I’m not going to do all of the things that they want to do. But they want to really cut it, and they want to cut it very substantially, the Republicans, and I’m not going to do that."

Pence supports raising the retirement age and fought adding prescription drug benefits to Medicare.

Trump brags that he opposed the Iraq War (which isn’t, you know, true) and made headlines for proposing a ban on Muslim travel to the US. Pence enthusiastically supported the Iraq War and took to Twitter to voice his disgust at Trump’s anti-Muslim policies:

Calls to ban Muslims from entering the U.S. are offensive and unconstitutional. — Governor Mike Pence (@GovPenceIN) December 8, 2015

Trump often angered conservatives by defending Planned Parenthood. "Planned Parenthood has done very good work for many, many — for millions of women," he insisted.

Pence has led the GOP’s war on Planned Parenthood. "He’s the only one I know of who has been so completely obsessed with Planned Parenthood," said the organization's president, Cecile Richards. "This just seems to be an enormous focus of his."

And then there’s Pence’s political style, and his political ties. He is pure Republican establishment. He was a leader of House conservatives before he became a leader of House Republicans before he became a leader of Republican governors.

Trump, of course, ran as the scourge of the Republican establishment. He welcomed their hatred, mocked their opposition, and humiliated their chosen candidates. Now he’s trying to marry into the family.

We cannot let the failing REPUBLICAN ESTABLISHMENT, who could not stop Obama (twice), ruin the MOVEMENT with millions of $'s in false ads! — Donald J. Trump (@realDonaldTrump) March 7, 2016

Similarly, part of Trump’s appeal was that he detested the role of money in politics. "When they call, I give," he said of his many donations. "And you know what? When I need something from them, two years later, three years later, I call them. They are there for me. And that's a broken system." He often bragged that he was self-funding his campaign — lobbyists would have no purchase in his administration.

Pence, by contrast, is an excellent fundraiser who is connected to both the business and ideological interests that contribute to the party. He hired top Koch operatives to senior staff positions, and is known for his close ties to Washington lobbying firms. Here, again, he is everything Trump isn’t, or at least everything Trump said he wasn’t.

A Pence pick is Trump deciding — or perhaps admitting — that it’s more important to be a Republican than to be, well, himself. Trump once had ambitions of upending the electoral map. He’s bragged that he would win New York and California, and he’s tried to make a pitch to disaffected Bernie Sanders voters. He could have chosen a vice president aligned with that strategy — an outsider, a businessman, a Californian, or at least a Republican who echoed Trump’s distaste for the GOP establishment. He could have doubled down on being different.

Instead, he looks to be choosing an emissary to the Republican Party, a VP who suggests that Trump’s deviations are part of a sales pitch, not core to his ideology or nonnegotiable in his approach to governing. In this, the highest-profile personnel decision Trump will make, he’s signaled either a lack of faith or a lack of commitment to Trumpism, and a desire to reconcile with Republicanism.

There are those, of course, who will say that picking Pence is just Trump consolidating his base — Trump is still Trump. But, then, that’s the whole point: If Trump will sell out Trumpism for Republicanism in a decision this important — a decision about who will lead the nation if Trump dies or is impeached or resigns to spend more time with his golf courses — he’ll do the same as president.

The political science that predicted Trump's rise