Aides said they hoped to group Mr. Trump’s executive actions thematically for maximum impact. They gave few other details, though some advisers suggested that executive actions on illegal immigration could be among the first issued after the inaugural weekend.

Advocates for undocumented workers are anxiously waiting to see what Mr. Trump will do.

If he moves aggressively, he could immediately overturn Deferred Action for Childhood Arrivals, or DACA — the program Mr. Obama created to protect young immigrants who were brought illegally to the United States as children, giving them legal status and access to work permits. Ending that program would put as many as 800,000 of them at risk of being removed from their families and sent to the countries they had left as children.

The White House could instead unwind the program slowly, giving the young people, often called Dreamers, more time before their immigration protections and work permits expire. Senator Richard J. Durbin, Democrat of Illinois, said on Friday that in a brief conversation with the new president, Mr. Trump had given him assurances about the program.

The president, Mr. Durbin said, told him that “we don’t want to hurt those kids; we’re going to do something.”

“Thank goodness he said that,” the senator added.

The president could also order federal agents to conduct workplace raids to crack down on immigration violations. He could take action against so-called sanctuary cities, those that shield undocumented immigrants from deportation. Or he could issue an order reinstating a program known as Secure Communities, in which the local authorities cooperated with federal agencies to detect and deport illegal immigrants.