NEW ORLEANS — Democrat John Bel Edwards won election on Saturday as the next governor of Louisiana, staking a rare victory for his party in the conservative South.

Edwards, a 49-year-old state legislator, defeated Republican U.S. Sen. David Vitter in a hotly contested runoff election that defied the political headwinds in a state where Republicans currently hold all statewide offices. After his defeat, Vitter announced he would not seek another Senate term next year.

With 99 percent of the precincts reporting, Edwards held a 56 percent to 44 percent lead.

Edwards thanked his cheering supporters and said the election confounded conventional wisdom that he could not win.

“I will not let you down,” he said. “This election shows us that the people of Louisiana in a time of deep cynicism about our politics and also our future, have chosen hope over scorn… and over a distrust of others.”

In a reference to Republican Gov. Bobby Jindal, who has been criticized for focusing on his presidential campaign at the expense of Louisiana, Edwards said the people of a state that is “embarrassed by the vanity and unrestrained ambitions of its leadership” have chosen to pursue a better future.

Vitter, 54, was haunted during the race by his entanglement in a 2007 prostitution scandal in Washington. After a bruising primary last month left state Republicans divided, Edwards seized the opening to become the only Democratic governor south of Virginia.

In conceding the election, Vitter said he will not seek re-election to the Senate after he finishes the last year of this term.

“I decided I wanted to pursue new challenges outside the Senate, no matter what,” he said.

He said he called Edwards to congratulate him.

“I’ve lost one political campaign in my life, tonight, and ironically it’s the campaign and the political effort I am most proud of — fighting shoulder to shoulder with you,” Vitter said to supporters.

Edwards, an anti-abortion, pro-gun Democrat, will replace Jindal, who is unpopular in his state and barred by term limits from seeking re-election. Jindal did not endorse a candidate.

Jindal, who last week ended his presidential candidacy, issued a statement congratulating Edwards.

“Now is the time for everyone to put politics and partisanship aside and make sure our new governor is ready on day one,” he said.