Washington discussed his views on politics with GQ, admitting that he's confused as to why Romney does not speak about his Mormon faith more often.
"He hasn't even brought it up," Washington said of Romney. "When I see him, he's always uncomfortable. You can see that uncomfortableness. Forget about his being Mormon. He hasn't said anything about his faith."
Washington also spoke about Obama's "legacy" as the first African-American president of the US.
"He's in the beginning of the third quarter. I don't know what his legacy is yet," the actor explained. "[Obama is] the first - that's a part of it. Like Jackie Robinson. But it just wasn't the first game; it was lasting the whole thing."
Washington was once rumoured to be playing Obama in a biopic on the president's life, but he later insisted that he's "too old" for the role.
The US presidential election will be held on Tuesday, November 6.