(Bloomberg Opinion) — Democrats are facing a challenge they haven’t confronted since the 1988 presidential election. They are trying to persuade enough Americans to kick a Republican out of the White House even though the economy is doing well. They failed that year – and as their latest presidential debate showed, so far they haven’t figured out how to meet the challenge this time either.

Early in that debate, moderator Judy Woodruff of PBS noted that “the overall U.S. economy right now looks strong” and asked the candidates what they would say to voters “who may not like everything President Trump does but they really like this economy.” Each of the candidates who responded denied her premise. They said it wasn’t really a strong economy after all.

One of their tacks was to bring up specific shortcomings of the economy. Senator Bernie Sanders of Vermont said we have the highest child-poverty rate “of almost any major country on earth” and that wage growth over the past year, at 1.1% after inflation, has been “not great.” Former Vice President Joe Biden said that “most Americans” would “have to sell something or borrow the money” to pay an unexpected $400 bill. Entrepreneur Andrew Yang said that depression, financial insecurity and student loan debt are at record highs.

Many of these specific complaints are false or overstated. America’s child poverty rate looks bad in international comparisons only if you are looking at relative poverty: the fraction of children in households making less than half the median income. That’s actually a measure of inequality. Look instead at levels of material deprivation among children, and the U.S. is in line with other countries. Child poverty rates have also been declining.

Wage growth during the past year was better than it has been for most of the past two decades; and it is as good a conjunction of wage growth and high employment levels as we have seen in this period.

Biden’s statistic about a surprise $400 bill is wrong. He almost certainly misunderstood a Federal Reserve finding that 61 percent of Americans would pay a $400 bill out of cash. The other 39 percent, it is true, would sell something or borrow the money, for example by running a credit-card balance. That doesn’t mean a majority of the population would “have to” resort to such measures.

Americans’ self-reported financial security is also holding up well. The percentage of Americans who tell Gallup they are worried about maintaining their standard of living has generally been falling. For three years running, majorities have said that their financial situations are improving.

While Democrats are straining to find gloomy statistics, almost every economic indicator is moving in the right direction. Employment growth and wages are up. Poverty is down.

The other main tack the Democratic candidates took was to deny that Americans consider today’s economy good. Biden and Yang were joined by Massachusetts Senator Elizabeth Warren and South Bend, Indiana, Mayor Pete Buttigieg in claiming that although gross domestic product and the stock market have been rising, ordinary Americans aren’t feeling good economic times. “This economy is not working for most of us,” the mayor said.

Many of these specific complaints are false or overstated. America’s child poverty rate looks bad in international comparisons only if you are looking at relative poverty: the fraction of children in households making less than half the median income

But most Americans don’t feel the way these Democrats say they do. As noted already, most Americans say their financial situations are getting better. The percentage of Americans who say it’s “a good time to find a quality job,” as another Gallup question puts it, has been at or higher than 50% for all of Trump’s time in office. It was below 50% for almost all of the George W. Bush and Barack Obama years. During the past two years, a majority of Americans has also rated economic conditions as excellent or good. They didn’t do that during the past two presidencies.

It is certainly possible for Democrats to argue that we could be doing better, or to deny that Trump’s policies are responsible for the health of the economy. A lot of positive economic trends have continued, but not accelerated, during his time in office. But to say that “the middle class is getting killed,” as Biden did at the debate, is to fly in the face not just of the economic data but of what most Americans think about their own lives.

Perhaps the bottom will fall out of the economy before the election in a way that few people now anticipate. If it stays on the same path, though, President Trump will campaign next fall on a simple economic message: He has been good for the economy and the Democratic nominee would be bad. On current form, the Democratic candidate will counter him by trying to convince Americans that the economy isn’t as good as it looks and they’re not doing as well as they think they are. And then they’ll switch the subject to how Trump is dangerously disconnected from reality.