GOP ticket: Republican presidential candidate Mitt Romney names Paul Ryan his No. 2

Romney was the subject of an April Fools prank in which Ryan played a role. Romney showed up at a supposed campaign event where he heard Ryan calling him "the next president of the United States" — only to find the room nearly empty.

Ryan has worked in Washington for much of his adult life, a contrast to Romney, who frequently emphasizes his experience in business. He is also well-known for his fiendish physical fitness workouts.

His congressional district in southeast Wisconsin has something of a bipartisan voting record. Obama took 54 percent of the vote there in 2008, while the congressman received 64 percent in winning re-election.

The bus tour takes Romney through Virginia, North Carolina, Florida and Ohio. All are battlegrounds where Obama won in 2008.

Associated Press writers Bob Lewis in Norfolk, Va., Brian Bakst in St. Paul, Minn., Thomas Beaumont in Des Moines, Iowa, and David Espo, Steven Peoples, Matthew Daly and Ken Thomas in Washington contributed to this story.