DONALD TRUMP has presided over a strong economy. Since his election, the S&P 500 index of big American firms has returned 37% and the unemployment rate has repeatedly hit 50-year lows. On September 6th the Labour Department reported that American employers added 130,000 jobs in August and that the unemployment rate held steady at 3.7%. But in recent weeks, some warning signs have flashed red. Interest rates on long-term bonds have fallen below those of short-term securities, historically a reliable sign that a recession is coming. A model developed by the Federal Reserve Bank of New York puts the odds that a recession might begin within the next 12 months at over 37%.

As the economic outlook has dimmed, Americans have become gloomier. According to an analysis of data provided by YouGov, a polling firm, public opinion on the country’s economic health is markedly more negative today than when Mr Trump took office. On January 21st, 2017, the day after his inauguration, 23% of Americans said they believed the economy was “getting worse”, 27% thought it was “getting better” and 35% thought it was “staying the same”. On August 31st, the most recent date for which figures are available, 31% of respondents said the economy was headed downhill, 28% said it was on the up and 26% said it was on a steady course. This is the first time in the president’s tenure when pessimists have clearly outnumbered optimists.

If the mood in American households continues to worsen, and people start pulling back on spending and hiring, the consequences for Mr Trump could be dire. There are just 14 months until the 2020 presidential election and the president has made the economy the main selling-point of his campaign. For now, it is a winning issue. A recent survey conducted by Gallup, a pollster, found that a solid majority of Americans support Mr Trump’s handling of the economy. On other issues, however—such as health care, education and foreign affairs—he receives poor marks. Mr Trump inherited a booming economy. If a downturn occurs, he will have to campaign on other battlefields.