More than a dozen top aides have resigned from the presidential campaign of former U.S. House Speaker Newt Gingrich, dealing a major blow to his struggling bid for the 2012 Republican nomination.

Among the 16 aides who quit Thursday were campaign manager Rob Johnson, spokesman Rick Tyler and several consultants in Iowa and South Carolina, two crucial states that will play an early role in next year's nominating process.

Gingrich has stumbled ever since announcing his White House campaign on May 11. He drew the wrath of Republican lawmakers when he denounced a House Republican plan to privatize Medicare, the government-run health insurance plan for senior citizens, as “right-wing social engineering.”

The frustration within the campaign grew when Gingrich left for a two-week cruise to Greek Islands with his wife.

Despite the resignations, Gingrich posted on his Facebook page that he will continue to pursue a “solutions-oriented campaign,” that “begins anew” with a major foreign policy speech Sunday in Los Angeles, California.

Two of the aides who left Gingrich's campaign are former aides to Texas Governor Rick Perry, who recently said he is considering entering the crowded field of candidates for the Republican nomination.

And former Georgia Governor Sonny Perdue, who was serving as national co-chairman of Gingrich's campaign, announced he is joining the presidential campaign of former Minnesota Governor Tim Pawlenty.