Mr Scaramucci has said Donald Trump would not be able to “handle the heat” of testimonies from some of his top officials and would leave office before he could be removed by the Senate.
He told MSNBC’s Joy Reid: “Those four people, whether it’s Mulvaney, Bolton, Giuliani, Pompeo – if they have to testify under oath, he has to leave.”
Mr Mulvaney and Mr Pompeo are current Trump administration officials, as acting White House chief of staff and secretary of state respectively, while Mr Giuliani is Mr Trump’s personal lawyer and Mr Bolton is a former national security adviser.
All four men were implicated by Gordon Sondland, the US ambassador to the EU, in an explosive impeachment hearing in November.
Mr Sondland testified that senior administration officials were aware of a scheme to inappropriately pressure Ukraine to help Mr Trump’s 2020 re-election campaign.
“Everyone was in the loop. It was not secret,” he told Congress.
Mr Scaramucci, who had an eventful 10 day tenure at the White House before being fired, also accused Republican senators of allowing Mr Trump to break the law.
“By the way, the people that work with him know that he’s amoral and they know he’s lawless,” the former official added.
“Just go back to what John Kelly [former White House chief of staff] said: ‘Hire a yes person, you’re going to get yourself impeached.'”
Republicans have resisted requests from Democrats for new witnesses and testimonies in the impeachment trial, which is expected to start in January.
Mitch McConnell, the Senate majority leader, reportedly wants a swift trial with few witnesses to shut down the impeachment process.
The Republican-controlled Senate is expected to vote against removing Mr Trump from office after bitter partisan debates in the House of Representatives.
However, Republicans leaders have come under pressure to ensure a fair trial as senators must take an oath to do “impartial justice according to the Constitution and laws” at the start of an impeachment trial.
Mr Trump was impeached on Wednesday over two articles – abuse of power and obstruction of Congress.
Impeachment proceedings have already been damaging for the president as a number of high-profile US diplomats and foreign service officials have testified about their concerns over his conduct.