The United States could pump $800 billion or more into the economy to minimize damage from the coronavirus outbreak if Congress passes a payroll tax holiday through year end, White House economic adviser Larry Kudlow said on Monday.

"We have an enormous fiscal plan. It's at least $800 billion and maybe more," Kudlow told reporters, totaling up actions already taken and tacking on Trump's hoped-for tax relief.

"We have roughly $400 billion in ... fiscal assistance" already in the pipeline, Kudlow, a top Trump adviser, said.

Asked in an interview with Fox Business Network if the United States economy was headed for a recession, Kudlow declined to answer but he acknowledged the pain the ongoing outbreak of COVID-19 was having across the country.

"We're going to be challenged. It's going to be tough," he said.

Wall Street took a nose dive earlier on Monday as S&P 500 companies lost more than $2 trillion in value in the first few minutes of trading and trading on the three main U.S. stock indexes was halted for 15 minutes as investors panicked about the virus' impact.