"AMERICA IS respected again" goes one of President Trump's refrains in political rallies. Sadly, it is one of his most blatant falsehoods. In reality, the prestige of the United States and its president has plummeted in the world's most important nations since 2017 — so much so that a full recovery may be a stretch even if Mr. Trump is voted out of office in November.

A survey this summer by the nonpartisan Pew Research Center in 13 leading democracies delivered results that ought to be sobering for Republicans as well as Democrats. They show favorable views of the United States reaching all-time lows in Pew's 20 years of polling in Britain, France, Canada, Japan, Australia, the Netherlands and Sweden. In only one of the surveyed countries, South Korea, did more than 50 percent of those polled have a positive view of the United States; the median rating was 34 percent. By way of contrast, in 2016, U.S. approval ratings in those same nations ranged from 57 to 72 percent.

Part of the double-digit decline in U.S. prestige in the past year can be traced to the covid-19 epidemic: The global consensus is that the United States has handled it terribly. In all, a median of 84 percent of those surveyed across the world said this country had done a bad job dealing with the coronavirus outbreak; only 15 percent said the U.S. performance was very or somewhat good.

But the greater cause of U.S. unpopularity, the survey makes clear, is Mr. Trump. The median percentage of those who said they have "confidence" that the U.S. president "will do the right thing regarding world affairs" stands at a rock-bottom 16 percent. Mr. Trump's ratings are not only far below those of Barack Obama, who in 2016 had the confidence of between 68 and 93 percent of those surveyed; shockingly, he inspires less trust in leading democratic countries than Russia's Vladimir Putin and China's Xi Jinping, who were rated positively by 23 percent and 19 percent, respectively. The highest-rated leader, unsurprisingly, is Germany's Angela Merkel, whom Mr. Trump has frequently disparaged but who was rated positively by three-quarters of those surveyed.

Global poll ratings can be mercurial. Views of the United States reached a nadir in several European countries following the invasion of Iraq in 2003, then soared after Mr. Obama's election. Yet while it's easy to anticipate an improvement if Democrat Joe Biden defeats Mr. Trump, Mr. Biden lacks Mr. Obama's star power. U.S. prestige is likely to remain depressed even if Mr. Trump leaves office; if he does not, the consequences will be profound.

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