In the event of a victory by Donald Trump in November, political analysis will take on a forensic cast. How did establishment politics — first in the GOP primaries, then in a national electorate — come to die?

Privately, Democrats would regret their selection of one of the most joyless, least visionary presidential candidates of recent memory. Publicly, they would blame trends that incubated within the Republican coalition, particularly a nativism incited by conservative media and carried by a candidate — alternately cynical and frightening — who is unbound by truth, consistency or decency.

And, by God, they would be right in much of this critique. But this is really only adequate to explain how Trump seized a powerful plurality of Republican primary voters. Stipulating a Trump victory, Democrats could not dismiss the winning coalition as an ocean of deplorables. If Hillary Clinton loses, it will be because she was the resume candidate in an anti-establishment wave election. It will be because she argued that America, with incremental corrections, is on the right track set by Barack Obama, while more than 60 percent of Americans believe the country is off course, and have thought so for years.

If Trump succeeds in essentially turning out the midterm electorate in a presidential year — whiter, older, angrier — the main, motivating issue may be the restriction of immigration. But the general atmosphere of contempt for government that helps Trump — of disdain for the weakness and incompetence of the political class — is due to the Affordable Care Act.

More than six years after becoming law, the proudest accomplishment of the Obama years is a political burden for Democrats. A recent Gallup poll found that a majority of Americans disapprove of Obamacare. The deeper concern for Clinton and her party comes deeper in the numbers. Only 18 percent of Americans believe the Affordable Care Act has helped their families; 80 percent say it has hurt or had no effect. A higher proportion of Americans believe the federal government was behind the 9/11 attacks than believe it has helped them through Obamacare.

The Affordable Care Act has come to embody and summarize declining trust in political institutions. The law was passed in a partisan march, without a single Republican vote. The system's federal website was launched with a series of glitches and failures that still make "healthcare.gov" a byword for public incompetence in the computer age. Only 17 state-based exchanges (16 states and the District of Columbia) were created. Of that number, four (Hawaii, New Mexico, Nevada and Oregon) have failed, and Kentucky's will be dismantled/shuttered next year. According to a recent report by the House Energy and Commerce Committee, the Oregon exchange received $305 million in federal funds but never created a functional website or enrolled a single person in private insurance online.

Premium costs in the exchanges increased about 12 percent nationwide from 2015 to 2016. Current rates are now being finalized, but it looks like the increase from 2016 to 2017 will be double that. "This suggests that the system is not finding its balance or approaching stability but actually getting more unstable," says Yuval Levin of National Affairs. "People just aren't finding the insurance offerings in the exchanges attractive, and the law leaves insurers very few options for improving them. The insurers are increasingly fleeing — a third of counties in the U.S. will have only one option in the exchanges next year. And there isn't much the administration can do about it."

Because of a poisoned legislative atmosphere, there is no prospect of legislative fixes to an unstable and perhaps unsustainable system of health exchanges. So President Obama is left to call a "Millennial Outreach and Engagement Summit" later this month, urging the kids to buy health insurance and right Obamacare's listing demographic ship. It is less a solution than a concession of helplessness.

Trump calls attention to these failures, while offering (as usual) an apparently random collection of half-baked policies and baseless pledges ("everybody's got to be covered") as an alternative. There is no reason to trust Trump on the health issue, but there is plenty of reason to distrust Democratic leadership. No issue — none — has gone further to convey the impression of public incompetence that feeds Trumpism.

If Trump wins, there will be a host of reasons, but one will be this dramatic failure of liberal governance.

— Michael Gerson's email address is michaelgerson@washpost.com.