“Richard Nixon’s crimes were committed purely in the interest of his own political gain,” Mr. Wallace told Mr. Howard before an audience of a few hundred after viewing the filmmaker’s new film, “Frost/Nixon,” which is about the only U.S. president to resign from office.

“I think to compare what Nixon did, and the abuses of power for pure political self-preservation, to George W. Bush trying to protect this country — even if you disagree with rendition or waterboarding — it seems to me is both a gross misreading of history both then and now,” Mr. Wallace said.