Trump corona

(CNN) -- President Donald Trump said Tuesday his forthcoming executive order barring new immigration will apply only to people seeking green cards, will last 60 days and won't affect workers entering the country on a temporary basis.

Spelling out details of the measure for the first time since tweeting late Monday he would "temporarily suspend immigration into the United States," Trump announced something short of a full halt on immigration amid the coronavirus pandemic.

Instead, he said the provision would amount to a 60-day pause only on people seeking permanent resident status in the United States.

He said he would review the executive order at the end of that period and decide if it should be renewed.

Trump emphasized the economic effects of the order, indicating it would "protect American workers."

Trump said the executive order is being written now and he is likely to sign it on Wednesday.

"The executive order is being written now as we speak, probably tomorrow," he said, noting that it will have certain exemptions.

Ahead of Trump's briefing late Tuesday, details of the plan were murky and some White House aides said there wasn't a great deal of clarity on how the order would come together. A person familiar with the matter said administration officials began working around the middle of last week on an executive order that would restrict immigration after Trump raised the matter privately with aides.

Trump's principal adviser on immigration, Stephen Miller, was involved in the discussions over the past several days, according to people familiar with the matter. Miller has long acted as a main internal advocate for limits on immigration through executive action.

Even so, the late-night announcement on Monday caught some administration officials off guard since the order wasn't finalized and some of its provisions hadn't been fully fleshed out. Facing criticism over his administration's response to the coronavirus, Trump had been impatient to announce the order, a person familiar with the matter said.

An administration official with knowledge of the process told CNN the order only addresses green cards because the temporary work visa portion is more complicated and needs more time to sort out, particularly given the fact that many of those currently in the US on work visas are working on things related to the pandemic, from workers at food processing plants to health care workers.

Even before Trump provided more specific details about his move, his reelection campaign and allies were already touting and defending the executive order, reflecting the political underpinnings of Trump's late-night announcement.

The move -- which could prove largely symbolic, given the restrictions on immigration already in place due to the coronavirus pandemic -- allows Trump and his campaign to play directly to his base on the issue of immigration, which the President believes won him the 2016 election and he hopes to use again in 2020.

The pre-buttals also reflected another reality: The final executive order may not stop all immigrant workers from entering the country. Already, administration officials have advised agricultural groups that seasonal farm workers won't be affected.