The move was hardly a surprise; Gingrich has spent months raising money, assembling a campaign team and visiting early primary states. He also quietly opened a campaign headquarters in Atlanta, and had long been scheduled to address the Georgia Republican Party Convention on Friday in Macon, Ga. Aides say that will be his first speech as a full-fledged candidate.
Gingrich stepped down from the House after four tumultuous years as speaker. The 67-year-old Republican has stayed in the public eye, and in recent months, he has blasted President Barack Obama's federal health care law.
The twice-divorced Gingrich has been working hard to gain social conservatives. He's highlighted his conversion to Catholicism after marrying his third wife.
The Associated Press contributed to this report.