WASHINGTON — The account from the former F.B.I. director James B. Comey of President Trump pressing him to drop an investigation into Michael T. Flynn, the former national security adviser, has escalated talk among the president’s critics that his actions may amount to obstruction of justice and grounds for impeachment.

“Asking F.B.I. to drop an investigation is obstruction of justice,” Representative Ted Deutch, Democrat of Florida, wrote on Twitter on Tuesday. “Obstruction of justice is an impeachable offense.”

But several legal specialists across party lines cautioned that talk of impeachment was premature while the facts remained unclear; the White House has denied that Mr. Trump pressured Mr. Comey to drop the case.

Still, the early chatter has heightened interest in how the impeachment process works. Here’s what you need to know:

What is impeachment?

The Constitution permits Congress to remove presidents before their term is up if enough lawmakers vote to say that they committed “treason, bribery, or other high crimes and misdemeanors.”