WASHINGTON (AP) -- The GOP presidential race can be summed up this way: three strong contenders and a hunger for someone else. ``There's no question that there's a very open field,'' said Ken Mehlman, a former Republican National Committee chairman. Unlike in 1980, 1988, 1996 and 2000, ``there's not a presumptive front-runner,'' he added. The nomination fight has become even more fluid since the year began, which is unusual for a party that typically has a clear heir apparent. For now, former New York City Mayor Rudy Giuliani has the lead in national popularity polls. Ex-Massachusetts Gov. Mitt Romney has...