Romney told conservatives gathered in Washington that if he were to continue his campaign, it would delay the launch of a national campaign against the Democrats. And he said he can't let himself be part of what he calls "aiding a surrender to terror."
McCain is now the top man standing in the GOP race, with Mike Huckabee and Ron Paul far behind in the delegate count. Just seven months ago, McCain was out of cash and losing staff.
As for Romney, the former Massachusetts governor launched his campaign almost a year ago in his native Michigan. He invested more than 40 million dollars of his own money in the race, and counted on early wins in Iowa and New Hampshire that never materialized. On Super Tuesday, he won just seven states, mostly small caucus states.