Alex Brandon / AP

Just as he has before, President Donald Trump may eventually retreat from his latest threat to shut down the federal government unless Congress provides him $5 billion for his border wall.

But Trump’s decision to rattle sabers this week over the wall—a proposal that about three-fifths of Americans have consistently opposed in polls—points toward a larger dynamic that appears guaranteed to shape his presidency through the 2020 election. Trump, the Republican congressional leadership, and most of the conservative-media infrastructure have all made clear that they see no need for a course correction after the midterms, even though Democrats won more than 53 percent of the total popular vote in House elections. That’s a larger share than Democrats have captured in any election since 1988, when most southerners still voted Democratic—or than the GOP has attracted since 1946.

Instead, the dominant reflex across the GOP this month has been to minimize the magnitude—and, equally important, the predictability—of the backlash against Trump that fueled Democratic gains in the House, state legislatures, and governors’ mansions. The party is steaming full speed ahead down the Trump track.

That choice testifies to the diminished appetite among Republicans to confront Trump, even as many GOP strategists privately acknowledge that the election offers powerful new evidence about the near- and long-term costs inherent in his path. “There’s still a fair amount of denial, and wishful thinking,” says the longtime GOP strategist Bill Kristol, a leading Trump critic.

One reason for the muted response among Republicans was that their losses, especially in the House, were not fully apparent on Election Night. Much of the instant television analysis focused on the GOP’s success in expanding its Senate majority by ousting several Democratic incumbents in states that voted for Trump in 2016, or on the narrow losses by the three young Democrats who captured the party’s imagination this year: African American gubernatorial candidates Andrew Gillum in Florida and Stacey Abrams in Georgia, and Senate contender Beto O’Rourke in Texas. These results allowed an array of Republican commentators—including Trump himself in his postelection press conference—to quickly declare the results a vindication. “President Trump will win reelection,” gushed the talk-show host and columnist Hugh Hewitt. “Anyone who watched Wednesday’s presser after Trump’s big night Tuesday knows in his or her bones that it will happen.”

Only a handful of conservative-media voices, most prominently The Wall Street Journal’s editorial page, raised alarms about the results. More telling is that hardly any party leaders have reconsidered their blithe initial reactions, even as vote counting since Election Day has mapped the full scope of the Democratic surge in the House.

Now, a few weeks out, the 2018 House results look like one of the most emphatic midterm repudiations of a modern president. With increasing indications on Wednesday that Democrats will win the last uncalled race, in California, the party is poised to gain 40 House seats, the most since the Watergate-era election of 1974.

The House popular vote offered an even more forceful statement: Democrats now lead the total vote count by about 9.1 million, or just over 8 percentage points, according to tabulations by David Wasserman of The Cook Political Report.

In raw votes, that’s the biggest margin ever for either party during a midterm election, according to calculations by NBC News. In percentage terms, it’s a bigger victory margin than the ones Republicans amassed in their 1994 and 2010 landslides, or that Democrats accumulated in their big 2006 win.

The composition of the Democratic gain was just as revealing as its size. The actual results almost perfectly tracked what might be expected from a lab experiment to measure how voters would sort in response to Trump’s agenda, which openly aligns the GOP with hostility to demographic and cultural change. Blue-collar, older, evangelical, and rural whites continued to provide Republicans with big margins almost everywhere, just as they did for Trump in 2016, and that support keyed the defeats of Democratic senators in North Dakota, Indiana, and Missouri.

But an exit poll conducted by Edison Research and election-result modeling from the Democratic targeting firm Catalist showed that Republicans faced high turnout and widespread reject among minority voters; the largest deficit among young people in decades, losing not only two-thirds of voters ages 18 to 29 but almost three-fifths of those 30 to 44; and a sharp movement toward Democrats almost everywhere among college-educated white voters, especially women.

Combined, these shifts swept away Republicans in affluent and in many cases diverse suburban districts nationwide. Before the election, Republicans held more than two-fifths of the House seats in which the share of college graduates exceeds the national average. They now control about one-fourth. “We are becoming older and more rural and less well-educated,” says the GOP pollster Glen Bolger.

Few in either party dispute that Trump could squeeze enough votes out of that coalition to win a second term—though signs of disaffection this month among working-class white women in the decisive Rust Belt states of Michigan, Wisconsin, and Pennsylvania are a blinking red light for him. The disproportionate influence of preponderantly white, rural states also makes his coalition competitive in the struggle to control the Senate. But as a long-term proposition, this election made clear that Trump is forcing the GOP to trade increased opposition among groups that are growing in society (minorities, Millennials, and white-collar whites, especially in metropolitan areas) for enhanced support among groups that are shrinking (especially non-college-educated and rural whites.)

Since the election, Republicans have demonstrated how reluctant they are to openly grapple with the transformation Trump is imposing on their party. But with their silence, they are cementing it.

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