Former Treasury Secretary Larry Summers thinks Donald Trump is the most dangerous threat to the nation and he could spark an economic crisis if the billionaire real-estate magnate is elected commander-in-chief.

“The possible election of Donald Trump as president is the greatest present threat to the prosperity and security of the United States,” Summers wrote in the Washington Post.

"I have had a strong point of view on each of the last 10 presidential elections, but never before had I feared that what I regarded as the wrong outcome would in the long sweep of history risk grave damage to the American project," he wrote.

“A growing sense that a protectionist demagogue could soon become president of the United States would surely introduce great uncertainty at home and abroad. The resulting increase in risk premiums might well be enough to tip a fragile U.S. economy into recession,” wrote Summers, who also was an economic adviser to President Barack Obama and served as Treasury secretary under Bill Clinton.

“Concern that the U.S. was becoming protectionist and isolationist could easily undermine confidence in many emerging markets and set off a financial crisis,” Summers explained.

“The sooner Donald Trump is relegated to the margins of our national life, the better off we and the world will be,” wrote Summers, now a Harvard professor.

"Donald Trump’s rise goes beyond his demagogic appeal," Summers writes. "It is a reflection of the political psychology of frustration — people see him as responding to their fears about the modern world order, an outsider fighting for those who have been left behind. If we are to move past Trumpism, it will be essential to develop convincing responses to economic slowdown," Summers warned.

For his part, Trump, casting doubt on the nation's economic health, has said the U.S. economy is in a bubble he fears will burst and he does not want to deal with a financial collapse if he is elected to the White House.

Trump cited the economy as one of the toughest assignments he would face as president if he wins the Nov. 8 presidential election, along with the Iran nuclear deal, Reuters reported.

"It's a very daunting task, and we're in deep trouble. The country's a mess," Trump recently told ABC's "Good Morning America" program.

"We're in a bubble," added Trump, the front-runner for the Republican presidential nomination. "And, frankly, if there's going to be a bubble popping, I hope they pop before I become president because I don't want to inherit all this stuff. I'd rather it be the day before rather than the day after, I will tell you that."

(Newsmax wire services contributed to this report).

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