The April 5 Republican primary in Wisconsin is looking less like a toss-up between Donald Trump and Sen. Ted Cruz and more like a probable win for Cruz. This would be a fairly grave problem for Trump in his effort to reach 1,237 delegates ahead of the convention. Further, a new Wisconsin poll from a well-respected outfit shows horrific favorability ratings for Trump in the state among all voters, mirroring his recent national downturn. If he can’t reach enough delegates ahead of the convention, and his support shows signs of erosion in the final contests—all while his overall favorability rating dives from pretty terrible to comically toxic—it’s going to be that much harder for him to convince delegates to stick with him in Cleveland.

The just-released Marquette Law School poll for March finds Cruz at 40 percent in the state, with Trump at 30 percent and John Kasich at 21 percent. Trump’s 30 percent is actually stable from the February version of the poll … when there were three more candidates still in the race. Cruz’s support, meanwhile, has shot up 21 points in a month, while Kasich’s has increased 13. The once dearly held theory of the Trump ceiling—that his support would never exceed one-third of the primary electorate and thus would not grow even once the field had consolidated—has been shattered in some states. If this poll holds, though, the theory appears to apply to Wisconsin.

One reason that Trump may be struggling in Wisconsin is that likely voters in Wisconsin despise him. The new Marquette poll finds his favorability rating at 22 percent, compared with a 70 percent unfavorability rating. That is … bad? No. It would be an insult to the quiet dignity of the word “bad” to call that spread bad. A 22–70 favorability spread is in the mid- to high “holy shits.” Sure, that number includes all voters, not just Republicans. But if Trump has a 22 percent overall favorability and 30 percent of the Republican vote, that means there aren’t a whole lot of Republican primary voters out there for him to sway.

The Marquette results are the latest to show the state slipping away from Trump as the contest approaches. And it’s not a write-off state for him, either, in the way that perhaps Utah was. Trump’s leads in the scattered Wisconsin polls conducted earlier this year factor critically into rough estimates of how he would reach a 1,237-delegate majority heading into the convention. A FiveThirtyEight delegate projection for Trump last week, compiled as an average of each staffer’s projections, showed him accumulating 1,208 before the convention—i.e., just short of the mark. And even there, staffers projected that Trump had to earn 25 delegates out of Wisconsin’s 42. Another comprehensive projection from the University of Virginia’s Center for Politics this past week put Trump’s final number just over the top at 1,239. In that projection, Trump earned 30 out of 42 delegates in Wisconsin.

If results like those in the Marquette poll hold, Trump would pick up delegates in the single digits, at best. Wisconsin effectively offers 18 delegates to the statewide winner and another three for each of its eight congressional districts. The reason Trump was able to win the vast majority of delegates in states like Missouri and Illinois, even with modest plurality support, was the breadth of his support: He led in both rural areas and voter-rich concentrations around cities, a consistency that ensured pluralities in a lot of congressional districts.

In Wisconsin, Cruz would flip the script. Trump is despised in the populous and very conservative Republican counties surrounding Milwaukee, an area from which several congressional districts draw their votes. The new Marquette poll finds Cruz with 53 percent support in Milwaukee City and County to Kasich’s 22 and Trump’s 15. Cruz leads Trump 43–27 in the rest of the Milwaukee media market. In the Madison market further west, meanwhile, Trump’s main opponent is Kasich—and Kasich leads Trump 37–33.* The only area where Trump leads is in the northwestern part of the state. That’s a lot of geographical area, but basically only one congressional district—or three total delegates, out of 42, that he’d have a strong chance of banking.

If Cruz can take most or all of Wisconsin’s delegates, Trump will have to pull off a surprise win or two of his own—or an absolutely dominant performance in the June 7 California primary—to make up for it. Otherwise, let’s just say it’s a good idea that he’s finally seriously developing a convention delegate strategy.

Read more Slate coverage of the 2016 Republican primary.

Correction, March 30, 2016: This article originally misstated the Madison media market is east of Milwaukee and its suburbs. It is to the west. (Return.)