Senator-Elect Doug Jones’ victory in Alabama should alarm Republicans in Congress — not so much because of why Roy Moore lost, but how.

Certainly, the allegations against Mr. Moore of sexual misconduct with teenage girls were more credible to voters than President Donald Trump and former strategist Steve Bannon calculated. However, Mr. Trump’s tweeting and generally controversial behavior has turned off many women and young people, along with black- and college-educated voters, as was also seen in recent gubernatorial elections in Virginia and New Jersey.

The president’s conduct has done little to dispel President Barack Obama’s warnings during the 2016 campaign that Mr. Trump is not suited by personality and background to be president, and that has motivated the Democratic base to turn out in huge numbers to vote against GOP candidates.

As importantly, Mr. Trump’s rants against political correctness and progressive personalities may bring thunderous applause at rallies. However, those comments have not translated into similarly large voter turnout among blue-collar, often conservative-Christian whites, whose economic fortunes have been damaged by free-trade policies, immigration and new technologies that ruthlessly undermine the economic futures of those with only a high school education.

If these trends continue, Democrats have a decent shot at flipping many of the 23 House seats occupied by Republicans from districts that went for Hillary Clinton in 2016 and at capturing both the House and Senate in 2018.

Americans have to feed their kids, and that may be the toughest everyday challenge for Trump voters.

His antics don’t solve their economic troubles. He has failed to sell just about anyone — other than professional conservatives among the Beltway intelligentsia and the occupants of corporate CEO suites — on the idea that his economic policies will do much to help the country at large, but in particular those stranded in rural areas and small cities left behind by the Obama recovery. Specifically, those Americans who delivered to him a peculiar Electoral College victory but not nearly a popular vote plurality.

His tax reforms will do most to help the prosperous middle and upper classes that already hold good jobs on the two coasts. Many are in high tax states and may be hurt by curtailing state and local tax deductions, but the combination of lower rates and stronger growth will leave them much better off in a few years.

A few extra dollars in the after-tax pay envelopes of the working poor and semiskilled worker will hardly compensate them for the declining conditions wrought by decaying infrastructure, more imports from China and competition from less-educated immigrants, who find their way into their communities that still have factory jobs to offer.

A lower corporate rate simply won’t bring back manufacturing to communities with inadequate roads, internet and health care, rampant opiate abuse, boarded-up main streets and distant opportunities for adequate vocational training.

The president’s infrastructure initiative will hardly scratch the surface of those problems, and Republicans’ ideas about health care reform — lax responses to the monopolization of hospitals, insurance markets and medical practices, and little appetite for price regulations — will likely make things worse.

Targeting specific industries — for example aluminum and solar panels — for tougher enforcement of trade laws against subsidies and dumping is proving inadequate to the broader structural failings of the WTO and U.S. policy to address the systemic inconsistencies between China’s socialist-market economy and market capitalism as practiced in the West.

Simply, the trade deficit with China and job losses continue to climb because the Trump administration is fighting a 21st-century trade war with weapons more appropriate to skirmishes with Japan a generation ago.

The popular sentiment to grant permanent status to the Dreamers — young adults brought into America illegally as young children — provides an opportunity to move toward an immigration policy that emphasizes highly skilled workers while limiting numbers of poorly educated entrants who often compete directly with Trump voters.

Instead, President Trump digs in on building a wall that not even his supporters along the Mexican border endorse; they believe the money could be better spent on more sophisticated intervention techniques.

No surprise, nearly a year into his presidency things aren’t getting much better in rural and small town America.

The shine on the Trump presidency is turning to tarnish, and Republicans in Congress will pay for this disaffection in 2018.

Peter Morici (Twitter: @pmorici1) is an economist and business professor at the University of Maryland, and a national columnist.