President Bush says Americans have "a duty to vote."
Speaking with campaign workers in Columbus, Ohio, Bush said he hopes for "a turnout as big as possible."
He told his supporters he's "confident" of a win in their state. No Republican has won the White House without Ohio.
While there, he made a few calls from a phone bank. He told one doubting recipient of a presidential call, "I promise you, it's me."
After leaving Columbus, the president headed to the White House to watch the results.
