The Irish actor, 65, is starring alongside Jeff Daniels in a miniseries based on former FBI director James Comey’s tell-all book A Higher Loyalty.
The Comey Rule, set to premiere in the US in September, explores the clash of personalities between the two men following Mr Trump’s election in 2016.
The 30-second teaser shows glimpses of Gleeson in Mr Trump’s trademark hairstyle while growling “I’m the president now” in an imitation of the president’s distinctive voice.
Who's as excited as we are for The Comey Rule?
Meet Jeff Daniels as FBI Director James Comey, Michael Kelly as FBI Deputy/Acting Director Andrew McCabe, and Holly Hunter as Attorney General Sally Yates. pic.twitter.com/H4z8DhSPVc
— SHOWTIME (@Showtime) July 29, 2020
The Comey Rule was initially set to premiere after November’s presidential election before writer/director Billy Ray shared a letter of apology to the cast noting his disappointment in the decision.
He said he made the project for his country and wanted to “get this story in front of the American people months before the coming election”.
Network Showtime changed course and the four-hour miniseries will now air over two nights, beginning on September 27, roughly six weeks before US voters go to the polls.
Holly Hunter, Michael Kelly, Jennifer Ehle, Peter Coyote, Steven Pasquale and William Sadler also star.
Mr Trump abruptly fired FBI director Comey in May 2017, saying it was necessary to restore “public trust and confidence” in the nation’s top law enforcement agency.
Gleeson is best known for film roles in Braveheart, Gangs Of New York and In Bruges, as well as for playing Alastor Moody in the Harry Potter movies.