LUTZ, Fla. — Republican presidential contender Newt Gingrich presented himself as the conservative alternative to rival Mitt Romney Sunday, labeling Romney a liberal who represents the insiders of Washington and Wall Street and vowing to remain in the race until the August convention.

“I am in fact the legitimate heir of the Reagan movement, not some liberal from Massachusetts,” Gingrich shouted to thousands of fired-up Floridians rallying in The Villages, a retirement community 60 miles from Orlando where golf carts outnumber cars.