Not every policy that parties pursue is popular. But for the modern Republican Party, almost all of its major policies and political strategies have failed to attain popular support.

That the party has seldom paid a price for that unpopularity points to a troubling feature of modern American democracy: It’s not that democratic. The reasons for that are complex. Some are institutional, like an Electoral College that’s increasingly tilted toward Republican voters and gerrymandered congressional districts that create one-party rule across vast parts of the country. Some are overtly anti-democratic practices, like voter restriction. Some are simply savvy politics, like messaging that disguises the actual policy up for debate, like the infamous labeling of inheritance taxes as “death taxes.”

However one weighs out these various factors, the overall picture remains the same: One of the two major parties no longer feels beholden to public opinion. And that’s why, even though an October Fox News poll indicated that 51 percent of voters favor both impeachment and removal for Mr. Trump, we shouldn’t expect Republicans in Congress to fall in line. Given that not a single House Republican voted yes during the public impeachment inquiry vote that they themselves had requested, we also shouldn’t expect Republicans in Congress to treat the impeachment vote and possible trial with a sense of sober responsibility. We’re no longer in the days of Watergate, where the cumulative weight of public opinion could stir, in addition to a sense of duty, a sense of self-preservation among congressional Republicans. The party has been practicing unpopular politics for decades, and Mr. Trump may well find himself its greatest beneficiary.