COLUMBIA, South Carolina: The governor of South Carolina, reportedly a 2012 presidential contender, tearfully confessed to having an affair with a woman in Argentina, dealing the latest blow to a struggling Republican Party.

Gov Mark Sanford, who caused a ruckus after he could not be located by staff, family and friends for several days, apologized to his wife and four sons and said he will resign as head of the Republican Governors Association.

"I've been unfaithful to my wife," he said in a bombshell news conference in which the 49-year-old governor ruminated aloud with remarkable frankness on God's law, moral absolutes and following one's heart. He said he spent the last five days "crying in Argentina." His family did not attend.