Victor Davis Hanson of National Review Online probes President Trump’s re-election prospects.

What factors usually reelect or throw out incumbent presidents?

The economy counts most.

Recessions, or at least chronic economic pessimism, sink incumbents. Presidents Jimmy Carter and George H. W. Bush were tagged with sluggish growth, high unemployment, and a sense of perceived stagnation — and were easily defeated.

The 2008 financial crisis likely ended any chance for John McCain to continue eight years of Republican rule. …

… A once-unpopular incumbent Ronald Reagan fought recession for three years. Yet he soared to a landslide victory in 1984 only after the gross domestic product suddenly took off at an annualized clip of over 7 percent prior to the election.

President Donald Trump’s economy is still booming. But his opponents here and abroad are counting on a recession to derail him.

They hope that either the good times can’t last forever or that Trump’s trade war with China will scare investors and businesspeople into retrenchment. Or perhaps massive annual deficits and staggering debt will finally catch up to a financially reckless government.

China will do all it can to prompt a U.S. downturn before November 2020 in hopes that it can get a better deal from a new Democratic president.

Unpopular optional wars are just as lethal to incumbents. …

… So far, Trump has been careful to avoid optional wars, nation-building, and even so-called “police actions.” North Korea and Iran both know that all too well. So, they are likely to push the envelope in the expectation that either Trump will have to backpedal in fear of defeat in 2020, or that his tough stance will disappear with the election of a more accommodating Democratic president.