In an interview with the Washington Post published on Saturday, the billionaire businessman said a combination of high unemployment and an overvalued stock market had set the stage for another economic slump.
He put real unemployment above 20 per cent.
"We're not heading for a recession, massive or minor, and the unemployment rate is not 20 percent," said Harm Bandholz, chief US economist at UniCredit Research in New York.
The official unemployment rate has declined to 5 per cent from a peak of 10 percent in October 2009, according to government statistics.
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But a different, broader measure of unemployment that includes people who want to work but have given up searching and those working part-time because they cannot find full-time employment is at 9.8 per cent.
Coming off a difficult week of campaigning, in which he acknowledged he struggled to articulate his position on abortion among other missteps, Trump's comments to the Post might be some of his most bearish on the economy and financial markets.
"I think we're sitting on an economic bubble. A financial bubble," he said.
Some economists agree the stock market is in a period of overvaluation but do not see that as foretelling a cataclysmic economic downturn originating in the United States.
"Nobody can predict what the stock market is going to do," said Rajeev Dhawan, director of the Economic Forecasting Center at Georgia State University.
"I cannot predict a stock market crash, so I cannot predict a recession. I don't see any of the reasons for a recession going forward unless there is a huge problem with the market or there is some catastrophic world event which is beyond the scope of economics."
Sung Won Sohn, an economics professor at California State University Channel Islands in Camarillo, put the probability of an imminent recession at less than 10 per cent.
"If it happens, it would be because of what is happening overseas, especially in China and Europe," he said.
'US still solid enough'
Joel Naroff, chief economist at Naroff Economic Advisors in Pennsylvania, said it would take a "total financial meltdown" to trigger a recession.
"We can get by with Europe growing minimally," he said.
"We can get by with China growing modestly because the rest of the US is still solid enough that we can handle weakness in the rest of the world."
The Democratic National Committee criticised Trump for his remarks, saying they "undermine our economy."
Trump's success with voters, despite his sometimes saying things only to contradict them later, has also alarmed many leading figures within his own party. Some of them are openly plotting to try to prevent him from becoming the nominee at the party's national convention in July.
Reince Priebus, the Republican National Committee chairman, said on Sunday that voters were "afraid" of their economic situation, when asked about Trump's remarks on CNN's "State of the Union" show.
"When people are afraid and when they're angry, sometimes people say things that they regret," he said, apparently referring to Trump's remarks.
He also played down speculation that party leaders would seek to dislodge Trump by helping someone who is not even a declared candidate prevail at the convention, which becomes governed by complicated voting rules if no candidate arrives with a clear majority.
"I think that our candidate is someone who's running," Priebus said, referring to Trump, US Senator Ted Cruz of Texas and Ohio Governor John Kasich.
The candidates will next face voters on Tuesday in Wisconsin, where recent polls show Cruz holding a small lead over Trump.
