On Oct. 28, 1980, in a final debate against Jimmy Carter, Ronald Reagan asked a question that defines presidential politics: "Next Tuesday all of you will go to the polls, will stand there in the polling place and make a decision. I think when you make that decision, it might be well if you would ask yourself, are you better off than you were four years ago?"

The answer for most voters was no, and Reagan won the election with 489 electoral votes to Carter's 49. The question has popped up many times since. "Are you better off than you were four years ago?" asked Bill Clinton in 1992. In 1996, Clinton declared, "We are better off than we were four years ago." "Are you better off than you were four years ago?" asked Barack Obama in 2008. It worked for Clinton, and it worked for Obama. Now, the question is whether it will work for Donald Trump.

The Democratic 2020 challengers face a problem: Unless there is an economic downturn, the answer to the are-you-better-off question will work in Trump's favor, not his opponent's. The jobless rate, 3.7 percent, is the lowest in half a century. June's report - 224,000 new jobs - brought a strong performance. The economy is growing at a better than 3% annual rate. Wages have grown 3.1% over last year with low inflation. Things could change. But barring a significant reversal, in 2020 most voters would likely say yes when asked if they are better off than four years ago. And then they would vote to re-elect the incumbent president. That leaves Democrats with the task of convincing millions of Americans to vote against their economic interests.

Some Democrats have chosen to argue there is something so wrong with the president - he's a racist, or an agent of Russia - that traditional measures of a successful presidency do not apply. For front-runner Joe Biden's entry into the race, his video focused on the August 2017 white supremacist rally in Charlottesville, in which a counter-demonstrator was murdered. "We are in the battle for the soul of this nation," Biden said. "If we give Donald Trump eight years in the White House, he will forever and fundamentally alter the character of this nation - who we are - and I cannot stand by and watch that happen." Kamala Harris chose another approach. "I know predators," the former prosecutor said, "and we have a predator living in the White House." Other Democrats have portrayed Trump as a threat to American values, the rule of law, and the "norms" that guide our politics and lives. The message: Yes, the economy is growing, unemployment is low, and wages are rising. But America under a re-elected Trump would become a racist dystopia in which all the beliefs Americans hold dear would be under siege.

Democrats hope educated voters will be susceptible to anti-Trump social pressures, to being shamed out of voting for the president. The idea is that those voters will focus on their objections to the way Trump has conducted himself in office - the tweets! - and not on the economic results of his presidency. Indeed, a number of polls have shown that a significant group of voters who are happy about the economy still plan to vote against Trump.

Democrats can't ignore the economy. So far, when they have addressed it, they have relied on the standard-issue Democratic critique of GOP presidents - that Trump is creating an economy that benefits only his rich friends. It's not clear how well that will work. As The Wall Street Journal editorial board pointed out, under Trump, "wages are rising at the fastest rate in a decade for lower-skilled workers, and unemployment among less-educated Americans and minorities is near a record low." The result of Trump's policies, the Journal argued, "has been faster growth and less inequality."

Millions of Americans are better off than they were four years years ago. The question will be whether that matters.

Byron York is chief political correspondent for The Washington Examiner.