Mary Landrieu of Louisiana Is Pushed to Runoff in Senate Race

NEW ORLEANS - Extending an expensive and largely negative campaign for one more month, voters in Louisiana sent Mary Landrieu, a Democrat and three-term United States senator, and her Republican challenger, United States Representative Bill Cassidy, into a runoff election set for Dec. 6.

Given Louisiana's nonpartisan primary system - in which all candidates run in a primary and, if no one wins a majority, the top two vote-getters compete in an election a few weeks later - runoffs are fairly routine here and one had long been expected in this race.

While the state Republican Party formally backed Mr. Cassidy this summer, another Republican, Rob Maness, a retired Air Force colonel with a strong Tea Party following, stayed in the race and was drawing 15 percent of the vote at 9:30 p.m. Tuesday. Numerous polls suggest that much of the vote that went to Mr. Maness will move to Mr. Cassidy in the runoff, putting him in a strong position to win.

Ms. Landrieu is the last Democrat representing a Deep South state in the United States Senate and the last Democrat in office in Louisiana to be elected statewide. She won runoffs in her first and second elections for the Senate, in 1996 and 2002, though neither by huge margins. Given the rightward drift of the state, and particularly of the once reliably Democratic voters of southern Louisiana, Ms. Landrieu may be facing her toughest Senate election to date.

'She's got to find a way to get to 30 percent' of white voters, said Roy Fletcher, a Republican political consultant in Baton Rouge. 'In this headwind, with Obama and et cetera, I'm not sure.'

Her case to the voters has centered on her clout as a long-serving senator, particularly in securing funding for local projects and post-hurricane disaster aid. Highlighting her role as chairwoman of the Senate Energy Committee, she has drawn support and campaign donations from leading figures in the oil and gas industry. Ms. Landrieu has distanced herself from President Obama on energy issues, but Republicans have zeroed in on a number of votes that put her on the same side as the president, who is deeply unpopular here, most notably on the Affordable Care Act.

'I think people are looking for change,' said Stacy Crovetto, 55, a retired schoolteacher who was voting at an elementary school in Luling, La., midmorning. 'I think health care is one of the biggest concerns. People are concerned about the changes that Obamacare has made.'

Mr. Cassidy, a gastroenterologist turned congressman, has run most of the race like a front-runner, keeping a relatively low profile and sticking to the script. In the two debates that have been held and in many of his campaign ads, Mr. Cassidy repeatedly tied Ms. Landrieu to Mr. Obama's policies.