Donald Trump’s victory in the 2016 presidential election hinged on votes from the industrial Midwest. Since Ronald Reagan, this region had largely voted blue during presidential elections until Trump cracked the code. There was a sense after Trump won that a “reordering” had taken place. Yet, many denizens of these same states—Michigan, Ohio, Wisconsin, and Pennsylvania (to name the most important to Trump)—didn’t get the memo ahead of the 2018 midterms.

Facing stiff headwinds that might normally result in a massive blue wave, Republicans are holding up about as well as one could hope at the national level. In states like North Dakota, they are even poised to defeat an incumbent Democratic senator next week. Yet (ironically?) Republicans are facing surprising resistance in (of all places) the Rust Belt.

As Vox’s Dylan Scott observes, “Incumbent [Democratic] senators in Ohio, Michigan, and Pennsylvania seem assured of reelection. Democratic Sen. Tammy Baldwin, a coveted target for Republicans, is leading by 10 points in Wisconsin, where Republican Gov. Scott Walker could finally lose a reelection campaign.”

Likewise, Michigan appears poised to elect a Democratic governor, and Pennsylvania’s incumbent Democratic governor looks like he’s headed for reelection. (Meanwhile, Ohio’s gubernatorial race to replace Republican governor John Kasich is looking like a nail-biter.)

“Republican leaders are increasingly worried that their candidates for governor and Senate are in political trouble across Michigan, Pennsylvania, Minnesota and other states that the party prizes, and that the difficulties could spill into House races that the G.O.P. needs to win in November to keep control of the chamber,” writes Jonathan Martin in The New York Times.

Just two years after Trump stunned the world, Republicans should be asking: Why aren’t these our voters?

First, the assumption that Trump’s victory in these states would usher in an era of GOP domination was presumptuous. As Hillary Clinton writes in her book, "If just 40,000 people across Wisconsin, Michigan, and Pennsylvania had changed their minds, I would have won.”

Second, it seems likely that, despite her Midwestern background, Clinton was a uniquely bad Democrat for this region. Clinton was viewed as too close to Wall Street and the Washington establishment—not to mention the policies of Bill Clinton—for her own good. This explains why so many political observers believe that Bernie Sanders or Joe Biden would have prevailed in 2016, had they won the Democratic nomination.

Could it be that 2016 was simply the perfect Rust Belt storm, pitting the best possible Republican against the worst possible Democrat?

One smart center-right observer, Henry Olsen, believes that Trump won because he uniquely understood what blue collar, working-class voters in that region cared about. After all, normal Republicans (who worried about things like entitlement reform and free trade) didn’t tend to fare well there. Per Olsen, struggling Republican politicians in these areas just aren’t Trumpy enough.

“ Just as the Obama coalition wasn’t transferable to midterm candidates (or to Hillary Clinton), it may be that these voters will only vote Republican when Trump is on the ballot. ”

According to Olsen, Trump was able to run as a populist outsider against Clinton and the establishment, whereas Rust Belt Democrats this year are simply running smarter campaigns. Writing about two prominent Democrats, Olsen observes: “ Ohio’s senior U.S. Senator Sherrod Brown has been running ads against unfair Chinese competition for years, and Indiana [another industrial Midwest state, albeit one that Mitt Romney carried in 2012] Senator Joe Donnelly is hitting his Republican challenger for allegedly shipping jobs overseas in his business.”

“With Trump in the White House, however, fighting for American jobs should be an issue Republicans own,” he continues. “But for that to happen, Republicans have to claim the field, and too many don’t.” (Note: Olsen’s column was written in August. In an e-mail, he tells me, “I’ve read that [Republican Mike] Braun is hitting Donnelly on trade now—and has been moving up in the polls.”)

Still, not everyone agrees that Republicans could win these states by replicating Trump’s populist rhetoric. There’s a reason that midterms are historically tough for the party in charge, and it stands to reason that people faring the worst would be the most fickle. “The main thing,” liberal columnist Bill Scher tells me, “is this is an electorate that is dissatisfied, in general, and is very quick to blame whoever is in charge—Republican or Democrat.”

Part of the problem is that the Rust Belt is the geographic center of what might be called the Trump coalition (older, working-class whites without a college degree). Trump basically traded in all of the GOP’s chips to win these votes—and with them, the Electoral College. And guess what? It worked! Nevertheless, just as the Obama coalition wasn’t transferable to midterm candidates (or to Hillary Clinton), it may be that these voters will only vote Republican when Trump is on the ballot.

Trump’s gambit was always risky for Republicans. The idea of reverse engineering a political party (see Trump’s embrace of tariffs) to win votes in a rapidly declining region of America—especially if it comes at the expense of conceding votes in thriving states like Texas, Arizona, and Nevada—was always fraught. But that assumption included Republicans being able to bank on the Rust Belt.

Based on the polls heading into Election Day, that bet looks increasingly dubious. It may only be “Trump country” every four years.