A senior adviser to Donald Trump is denying that White House and administration officials scrambled to craft an executive order freezing most immigration into the United States following a late-night tweet by the president.

The White House counsel's office and Justice Department's Office of Legal Counsel reportedly sprung into motion after Mr Trump fired off a tweet at 10.06 pm Monday announcing an immigration freeze due to the coronavirus outbreak and economic slowdown.

"In light of the attack from the Invisible Enemy, as well as the need to protect the jobs of our GREAT American Citizens, I will be signing an Executive Order to temporarily suspend immigration into the United States!," the president wrote.

The president had not mentioned an immigration freeze during a nearly two-hour press briefing earlier that evening. Some Democratic leaders accused the president of trying to distract from governors' ongoing warnings about a lack of Covid-19 testing kits, even as Mr Trump called on governors to bring re-opening their states.

But his new press secretary, Kayleigh McEnany, told reporters Wednesday that administration officials had prepared a draft executive order to put the freeze in place prior to the president's tweet.

"That absolutely is not the case," Ms McEnany said. "In fact, I read the draft before the tweet even went out. So this has been in the works for quite some time. We're putting the final touches on it. We do expect to have that today."

Mr Trump on Tuesday evening, during his latest coronavirus press conference, told reporters he decided to freeze the issuing of all green cards for 60 days to "take care of the American worker."

"By pausing immigration, we'll help put unemployed Americans first in line for jobs as America reopens. So important," he said.