Senior Perry aides, friends and staff members told Reuters that after a restless night, Perry and his staff ultimately decided there were four reasons the campaign should continue.

Most significantly, his team essentially calculated that Rick Santorum, who emerged in Iowa as the leading conservative alternative to former Massachusetts governor Mitt Romney, isn’t a strong enough candidate to hold that position in future contests.

Perry’s campaign also received calls from supporters in Texas, who urged the governor not to give up. And Perry aides determined that their campaign – more so than those of Santorum, a former U.S. senator from Pennsylvania, or former House speaker Newt Gingrich – had the organization and fund-raising abilities to compete with Romney in the South Carolina primary on January 21.

Finally, Perry decided that he did not want to leave the race without competing in South Carolina, a state whose conservative voting base is more in line with his politics than middle-of-the road Iowa or New Hampshire, which will hold its primary on Tuesday.