A middle ground and second option urged by some legal experts is to allow prosecutors to obtain an indictment but defer further proceedings until the president leaves office.

The third option is impeachment, and prosecutors may present the evidence they have gathered to the House for its consideration.

Prosecutors in Manhattan, Mr. Lacovara said, “could seek permission from the deputy attorney general to do what we did in Watergate, which was to prepare a ‘road map’ of evidence bearing on the president’s culpability and send it to the House Judiciary Committee, which has jurisdiction over impeachment.”…

If Mr. Trump were to be treated as any other candidate — that is, not as president — he would likely face charges similar to those Senator John Edwards of North Carolina faced when he was indicted on a charge of suspected campaign finance violations in 2011. Those charges carried a combined maximum sentence of 30 years in jail and more than $1.5 million in fines.