"Mitt's choice for VP is Paul Ryan. Spread the word about America's comeback team," a Romney campaign app said, confirming widespread reports he had selected the 42-year-old Wisconsin lawmaker who chairs the U.S. House of Representatives Budget Committee.

Romney was expected to introduce Ryan at the retired battleship USS Wisconsin - coincidentally named for Ryan's home state - in Norfolk, Virginia, at about 9 a.m. EDT (1300 GMT) Saturday, a Republican official who asked not to be identified said late Friday.

The announcement will mark the end a months-long search by Romney for a running mate to join him in facing Democratic President Barack Obama and Vice President Joe Biden in the November 6 election.