How many political lives does President Trump have? He has survived the Mueller report, and his approval ratings remain stable as House Democrats begin impeachment proceedings. And now, a forecasting firm predicts Trump will win re-election, if the economy alone is the determining factor.

Oxford Economics predicts Trump will win 55% of the popular vote in 2020, with Democrats taking 45% in a two-party race. Since Trump won the electoral college in 2016 with just 46% of the popular vote, he could win by a larger electoral margin if he actually wins a majority of the popular vote.

Oxford bases its forecast on three economic factors that have traditionally determined whether voters are satisfied with the incumbent president or restless for somebody new: the unemployment rate, wage growth, and inflation. The firm forecasts unemployment to remain low throughout 2020, with the unemployment rate at 3.5% on Election Day. Real income growth should be around 0.5% per year, and inflation should be low, as it is now. The Oxford model has predicted the popular-vote winner in all but two presidential elections since 1948.

Similar analyses by Moody’s Analytics, Trend Macrolytics and others have also forecast a Trump win, based on an Election Day economy that looks more or less like it does now. A stable and growing economy normally favors an incumbent president running for releection, since voters don’t like to change what’s working.

The Oxford analysis doesn’t account for the unique elements of the Trump presidency, such as numerous scandals and Trump’s persistent unpopularity. “The model pays no attention to candidates’ attributes such as race, gender or ‘likeability,’ a factor that may be centrally important in 2020,” the Oxford analysis says. That’s a modest way of saying Trump could lose, even though he shouldn’t.

For one thing, it’s possible he won’t even be the nominee, if impeachment proceedings discover new smoking guns or the Republican Party mounts an insurrection against him. If Trump is the nominee, he’ll have to explain positions on guns, trade, immigration and health care that are out of step with the general population. Trump is already behind in key swing states he won in 2016, such as Pennsylvania, Ohio and Wisconsin, according to polling firm Morning Consult. And many polls show Trump losing in head-to-head matchups with possible Democratic nominees such as Joe Biden or Elizabeth Warren.

The economy could also be weaker than expected, especially if Trump’s trade war escalates. The Trump tariffs on China and other protectionist measures have already hurt the US economy and killed 300,000 jobs or more. Tax cuts that went into effect in 2018 aren’t helping. They contributed to a small investment boom in 2018 that has since petered out and are now causing a spike in federal deficits. Trump has proved his critics wrong many times, and may do so again. But he could also press his luck one too many times.