The Hollywood heartthrob was joined by Ryan Gosling at the Los Angeles premiere of the political thriller - which he co-wrote and directed as well as playing Governor Mike Morris, a Democratic presidential candidate on a fast track to the White House.
Clooney told The Daily Telegraph: "I don't know whether anyone can do this cleanly."
He went on: "I spent 16 weeks in an office on K street with Republican operatives, Mary Matalin, Michael Deaver and James Carville. I worked with a bunch of them and I saw just how difficult it was for anyone in the political arena, on either side to not have to shake hands with people that made them not feel clean."
The Ides of March follows the frantic last days of campaigning before a heavily contested Ohio presidential election.
Gosling plays an ambitious young press secretary who finds himself caught up in a political scandal that threatens to ruin his candidate's chances of winning.
The Ides of March also stars Jeffrey Wright, Marisa Tomei, Philip Seymour Hoffman and Paul Giamatti and opens in UK cinemas on Friday 28 October, after a premiere at the BFI London Film Festival.