Former Treasury Secretary Larry Summers reportedly has put the chances of a U.S. recession at 50 percent within the next two years.

The Harvard economist recently told CNBC that a slowdown in growth was a "near certainty" before adding "the recession risk is nearly 50 percent over the next two years, maybe slightly less."

He also said it is "crazy" that the U.S. hasn't fixed its airports and highways.

Summers also says the Fed should be careful about raising rates too quickly.

"I think the risks if we have a recession are very, very serious so they need to bend over backward to avoid that," he said.

However, he is optimistic about a bipartisan deal to build infrastructure.

"It is crazy that a country that can borrow for 30 years at 3 percent in a currency that we print ourselves isn't repairing its airports, our highways, and isn't putting in place a modern infrastructure."

Summers isn't alone in his pessimism.

JPMorgan Chase & Co. Chief Executive Officer Jamie Dimon agreed that while the U.S. economy is leading a global resurgence, the prospect of a recession as soon as 2020 can’t be ruled out.

“The consumer balance sheet is in good shape, corporations are in good shape. That may very well continue,” Dimon said Thursday in an interview with Axios in Columbus, Ohio. 

“2019 could be the fastest global growth year on record,” Dimon said.

Asked when the economy might start to contract, he said “that may very well happen in 2020, 2021.”

Meanwhile, JPMorgan Chase's retail chief predicts that worry over impending U.S. recession might actually cause one.

"This late-cycle recession has the potential to become a self-fulfilling prophecy," JPMorgan Chase Co-President Gordon Smith recently said during a financial conference held in New York, CNBC.com reported.

"There is a great deal of volatility in the equity markets, a great deal of conversation around how late we are in the cycle and worry about the cycle," Smith said.

"That will ultimately lead to business confidence deteriorating, it will ultimately lead to [corporate] reductions in spending, that will ultimately lead to a shorter work week for hourly-paid people, which will ultimately lead to unemployment beginning to rise, and we would've developed our own recession," Smith said.

Smith, who runs JPMorgan's consumer banking division, says the U.S. economy looks "extremely strong," CNBC.com quoted him as saying.

• Jamie Dimon: Recession Possible by 2020 Despite Strong Growth
• Martin Feldstein: Falling Stocks Will Spark Long, Deep Recession