Mississippi Gov. Haley Barbour ruled out a 2012 presidential bid on Monday, saying he lacked the necessary “absolute fire in the belly” to run and wasn’t ready for the “all-consuming effort.”

The announcement was unexpected, given the two-term governor’s recent visits to several states with early presidential contests, including Iowa, New Hampshire and South Carolina. He also had lined up political advisers for a possible run, and he had tested an economy-focused campaign speech in Chicago last month.

The stout governor had even lost some weight as advisers had suggested.

“I will not be a candidate for president next year,” the Republican, 63, said in a news release. “This has been a difficult, personal decision, and I am very grateful to my family for their total support of my going forward, had that been what I decided.”

“A candidate for president today is embracing a 10-year commitment to an all-consuming effort, to the virtual exclusion of all else,” Barbour said in his statement. “His (or her) supporters expect and deserve no less than absolute fire in the belly from their candidate. I cannot offer that with certainty, and total certainty is required.”

Barbour, a fiscal and social conservative and an accomplished fundraiser, would have been a formidable contender had he entered the race. His hurdles to the GOP nomination would have been high, too. He’s a former lobbyist and former Republican National Committee chairman who would have tried to woo a GOP primary electorate that’s underwhelmed by Washington insiders.

Wrote Barbour: “Hundreds of people have encouraged me to run and offered both to give and raise money for a presidential campaign. Many volunteers have organized events in support of my pursuing the race.  Some have dedicated virtually full time to setting up preliminary organizations in critical, early states and to helping plan what has been several months of intensive activity.

“I greatly appreciate each and every one of them and all their outstanding efforts. If I have disappointed any of them in this decision, I sincerely regret it,” he added.

Barbour was first elected Mississippi governor in 2003, and his first term was defined by Hurricane Katrina, which left a wide swath of destruction across south Mississippi when it struck in August 2005. He persuaded federal officials to give Mississippi billions of dollars for storm recovery, and he easily won a second term in November 2007.

As chairman of the Republican Governors Association from June 2009 through November 2010, Barbour traveled to dozens of states to campaign for GOP candidates, and it was widely believed he would use that perch to run for president.

Barbour, a native of Yazoo City, was political director for the Reagan White House in the mid-1980s, then helped found the Washington lobbying firm Barbour Griffith & Rogers in 1991. The firm’s client list included a  range of corporate interests, from Microsoft to tobacco and utility companies.

Barbour was RNC chairman from 1993 to 1997. In 1994, he helped the GOP take control of both the U.S. House and Senate for the first time in 40 years.

While building his political and lobbying career, Barbour split his time between Mississippi and Washington. His wife, Marsha, remained in Yazoo City to raise their two sons, who are now grown.