"Yeah I did," Howard said at a discussion following a Hollywood screening late last month. "You see now, that was a long time ago."
Five years later, Nixon granted English journalist David Frost the famous four-part interviews upon which the film is based.
Howard supported Democrat Barack Obama in the 2008 election with a viral video in which he said, among other things, that he'd voted for both parties in the past.
Howard said his draft number was 41, meaning he was close to being shipped off to the Vietnam War. Both Nixon and Democratic nominee George McGovern said at the time they would pull out of Vietnam, Howard recalled.
Nixon won re-election in a landslide.
Five years later, he admitted to English journalist Frost that he may have broken the law in the 1972 break-in of Democratic National Committee headquarters at the Watergate complex and subsequent cover-up.
Howard, 54, recalls watching the interviews on TV and explained his earlier vote may have helped him have sympathy for Nixon.
"I went into the interviews not as a Nixon hater, but having felt wounded by Watergate and betrayed as an American," he said. The interviews "were very cathartic to me."
In another admission, screenwriter Peter Morgan told the same screening audience that Nixon's fictionalized high-tension phone call to Frost one night between interview sessions did not actually happen, but was plausible because Nixon mixed alcohol with mood stabilizers.
"We know he made late night phone calls. He didn't remember them," Morgan said, adding "I had what I felt got to the heart of Richard Nixon" including a tendency to "destroy himself."
"Frost/Nixon," a Universal Pictures release, hits theaters Friday.