WATCH: Here's how impeachment could force Trump out of office

On Tuesday, President Donald Trump's former lawyer Michael Cohen pled guilty to multiple crimes, naming the president a co-conspirator in campaign finance violations.

Axios reports that overnight, people close to the president have become very worried.

"I must admit a bit of concern about what he [Trump] would do fully backed into a corner," a close friend of the president's told Axios.

"Trump folks are worried about impeachment more than before. ... Does not mean it will happen, but this has moved to a different stage in their minds," tweeted Maggie Haberman.

If Democrats gain a majority in the House this November, there's a very real possibility lawmakers might launch impeachment proceedings.

On MSNBC Wednesday, host Ali Velshi presented a primer on what the impeachment process would look like.

"First of all, the House of Representatives draws up articles of impeachment. Think of the House as the prosecutor," Velshi said.

"Any Congressperson can start this process," Velshi notes.

A simple majority is needed for the articles of impeachment to pass (Velshi erroneously said it required 2/3rds and later corrected that error).

If the articles of impeachment get to the Senate, 60 out of 100 senators must vote for impeachment for the president to be forced to leave office.

"If they do, the President is removed from office," Velshi noted. "The vice president would then take his place."

Watch: