Trump and Putin’s long-distance bromance has some consequences among Eastern European voters. Photo: Alex Wong/Getty Images; Sergei Ilnitsky/AFP/Getty Images

Donald Trump’s white working-class support might have some unexpected holes in key battleground states — specifically, among Americans of Eastern European heritage who are likely to look askance at the mogul’s man-crush on Vladimir Putin and his expressed reluctance to defend potential victims of Russian aggression. Russia’s own apparent interest in seeing Trump take power in Washington is likely problematic too.

As the Washington Post’s James Hohmann notes today, such voters — known once upon a time as an important element of the “Reagan Democrats,” who gave Ronald Reagan his demographic breakthrough — are very important to Donald Trump’s path to victory:

John Weaver, who was John Kasich’s chief strategist this year and advised both of McCain’s presidential bids, thinks the blowback is starting to show up in polls, specifically Trump’s weakness among Catholics who regularly attend mass.

“In and around Cleveland, Akron, Toledo, Detroit and all throughout Wisconsin, you’re talking about voters with family in Poland, the Baltics, Ukraine and the Czech Republic,” said Weaver. “These voters are key to any narrow path that Trump has left.”

Hostility toward Russia had something to do with the defection from the Democratic Party of Eastern European Catholic and Orthodox voters, who were attracted to Reagan’s “evil empire” rhetoric toward Moscow. Now the shoe is on the other foot, at a potentially serious cost to Republicans accustomed to carrying these voters.

Angst over Trump’s Russophilia is particularly intense among Ukrainian-Americans, as the New York Times’ Sheryl Gay Stolberg reports.

Ukrainian-Americans have felt at home in the Republican Party since Franklin D. Roosevelt and Stalin divided control of Europe at Yalta. But across the United States — and especially in swing state Ohio, where Mr. Trump became the party’s nominee — they are watching the 2016 presidential race with a mix of confusion and fear.

That figures. Ukraine isn’t just a contemporary object of Russian neo-imperialism. It was the subject of Stalin’s first great atrocity: the deliberate starvation of millions of people in the USSR’s breadbasket in the early 1930s as part of a campaign for forced collectivization of farms and the confiscation of grain to feed favored (mostly Russian) cities. And Ukraine suffered nearly as much as neighboring Poland during and after World War II, caught between Nazi and Soviet killing machines. Strong and reasonable suspicions that Trump (until recently guided by Paul Manafort, someone actively involved in the ongoing Russian campaign to reabsorb Ukraine) would turn a blind eye to Russian aggression is bound to be a real and practical problem for the GOP in this particular demographic.

Trump would be well-advised to spend some time with old-school cold warriors who can get him into the habit of insulting Putin the way he insults so many others. Otherwise the legendary bars and bowling alleys of places like Parma, Ohio, with sizable Eastern European populations, could become an unlikely graveyard for his presidential campaign.