Every shrewd politician keeps a watchful eye on his base, but the relationship between President Trump and his core supporters has become an object of near-fetishistic obsession. Even as his poll numbers continue to gradually settle toward the basement, Trump’s more outlandish actions are often interpreted as base maintenance, and it’s said that Trump’s base remains unshakably loyal to him.

A Wall Street Journal/NBC News poll released Thursday suggests this is half-right and half-wrong. Trump’s base does appear to be shrinking, but the people who are sticking with Trump are true diehards.

The idea of a shrinking Trump base is not new. In May, Nate Silver pointed out that the group of people who “strongly approve” of Trump was down. Steven Shepard noted in August that the president’s approval among Republican voters had decreased. And Brendan Nyhan argued that the base might never have been big as anyone thought anyway, because some anti-Trump Republicans would just quit identifying as Republicans, leaving an unrepresentative sample.

But the WSJ/NBC poll offers actual evidence of voters drifting away from Trump. For the last few months, the pollsters have been asking Republicans and Republican-leaning voters to say, regardless of their feelings about him now, whether they supported Trump in the GOP primary. Since April, that number has been steadily sinking, from 46 percent in April to 39 percent now. In fact, Trump won about 45 percent of the Republican primary vote. That’s a sure sign of base erosion: Not only are Republicans writ large drifting away from Trump, some voters who backed him are no longer willing to admit they did so.

That’s worrisome for Trump. Despite the overwhelming opposition of many Republican officials and institutions, despite winning only a plurality of the GOP primary vote, despite the release of a video in the last weeks of the campaign in which he boasted about sexual assaults, Trump was able to put together a winning coalition of Republicans and become president. If he hopes to win reelection, he’ll need woo them all back.

Before Trump unified the GOP, though, he had his own fanatical base. And those people aren’t just sticking with him—they adore him, still. Overall, voters in the poll are 52 percent negative on Trump, 36 percent positive, and 12 percent neutral. (Hillary Clinton’s numbers, for what it’s worth, are even worse—53/30/17, respectively.) But among self-identified Trump voters, an astonishing 98 percent approve of his performance. That sort of unanimity is unheard of, especially given Trump’s travails over the last seven months. Presumably, if the Trump primary voters who no longer identify as such were included, that number would decrease some. Among Republicans who say they voted for another primary candidate, only two-thirds approve of Trump. The overall approval among Republicans is 80 percent.

These voters are the hardcore Trump base one hears so much about. They are culturally conservative: More than six in 10 said they were uneasy about social changes, versus just 35 percent of Republicans who said they voted for other candidates in the primary. Fifty-six percent still oppose gay marriage, significantly more than the number of non-Trump GOP primary voters (45 percent) who agree. An even half said immigration affected their vote, more than double the 24 percent of non-Trump GOP primary voters who said the same.

In other words, these are the voters who are big fans of the border wall, and who support controversial moves like ending the DACA program. They weren’t appalled by Trump’s comments after Charlottesville endorsing a “soft” white supremacy; they see themselves when Trump says there were good people marching alongside the Klan and neo-Nazis, and they don’t agree with condemnations from Republicans like Senator Bob Corker of Tennessee.

These voters are also the ones who are likely to see Trump striking a deal with Nancy Pelosi and Chuck Schumer on government funding, disaster relief, and the debt ceiling, and who blame Paul Ryan and Mitch McConnell for it. For institutional pre-Trump Republicans, Pelosi is perhaps the villainess par excellence, and cutting a deal with her is a Faustian bargain, only without the upfront benefits but all of the soul-selling. But for the 98 percent of Trump voters still willing to admit they backed him in the primary, who see him as nearly incapable of doing any wrong, this is no sin, but rather proof of Ryan and McConnell’s fecklessness. My colleague Conor Friedersdorf spotlighted examples of this tendency among Trump’s media defenders yesterday, such as Breitbart and Lou Dobbs, and one might expect that their viewers are part of the hardcore group.

What these poll results suggest is that while Trump was able to cobble together a winning Republican coalition in November, his efforts to remake the GOP in his image are—like most of his major initiatives—still rather embryonic. There remain two Republican parties, one a Trump faction and one a rump faction. In the coming months, the president could reconquer the territory he has lost; or the two parts could remain at odds. It’s difficult to imagine the institutional GOP gaining supremacy as long as Trump remains president, but if he can’t unite them, he’ll struggle to win a second term.

The 98 percent approval shows that Trump’s base remains a fearsomely devoted bunch. Even Barack Obama, who inspired his own feverish fanaticism among fans, never reached those heights. But while the base is not faltering in its support, it is also not a solid, immutable object. Enthusiasm wins elections, but only if there are enough enthusiastic voters.