Republicans are counting on a strong economy to re-elect President Donald Trump but off-year elections in Virginia, Kentucky, Louisiana and Mississippi indicate he is in trouble.

Relying on historical voting patterns, a widely respected model built by Yale University economist Ray Fair predicts a Trump majority in the popular vote. Similarly, Oxford Economics gives the president a five-point win.

What those models miss is that voters' perceptions — not the real economic numbers — and to whom they assign credit are what count. Those are becoming increasingly more tribal.

More than 80% of Republicans are happy with the economy but fewer than 40% of Democrats. Political scientists find consumer confidence and presidential approval ratings correlated strongly from Presidents John F. Kennedy though George W. Bush but have been statistically disassociated for both Presidents Barack Obama and Trump.

A recent New York Times Upshot and Siena College survey indicate the president remains highly competitive in six battleground states — Michigan, Pennsylvania, Florida, Arizona and North Carolina. Even if he loses the popular vote by a larger margin than in 2016, he could eke out an Electoral College majority by winning Florida with its 29 electoral votes and two or three of the others if the rest of the country map goes the same as in 2016.

I would not bet on the latter — even in some "safe" Republican states.

These days, Americans are less focused on the big macroeconomic numbers-stronger wage growth and low unemployment-and are more troubled by skyrocketing prescription drug and health insurance costs, roads and other transportation solutions, college tuition and student loans, and the wage/opportunity gap for women.

Trump promised to fix these and other problems and simply hasn't much to show. His denials about climate change fly in the face of facts. Witness increased incidents of severe hurricanes, flooding, and wildfires in California — PG&E's transmission lines did not suddenly become rickety.

Mostly moderate Democrats flipped 40 House seats in 2018 by focusing on practical solutions to many of these problems.

Joe Biden's low energy and poor organization in places like Iowa and absence of creative ideas handicap him against Sen. Elizabeth Warren, and she is emerging the likely Democratic nominee. Republicans are banking that her heavy tax and regulatory approaches to reworking health care-ending private insurance-would make her an easy target.

Three of the last four presidents tried to reinvent healthcare but failed. Obamacare didn't bend the cost curve but instead has proven just a cumbersome subsidy program to help working Americans and the poor better obtain health insurance.

Peter Morici is an economist and business professor at the University of Maryland, and a national columnist. He tweets @pmorici1