U.S. Sen. Mary Landrieu (D-LA) lost roughly one-third of her support among white voters in Tuesday's election, based on an analysis of sample precincts.
A more thorough picture will come into view later this week when the Louisiana Secretary of State's office releases more detailed numbers.
However, a sampling of model precincts conducted by the polling firm Multi-Quest, Intl. shows Landrieu garnered 21.5 percent of the vote in precincts with 90 percent or higher white voter registration. In the 2008 race, Landrieu got about 32 percent of the white vote.
Pollster John Grimm found 55.5 percent of white voters in the sampling chose Bill Cassidy compared to 19.3 percent for Rob Maness.
Despite strong early voting numbers, lighter-than-expected turnout in some areas may have affected the outcome Tuesday, according to Grimm. Landrieu, a three-term incumbent, finished with 42 percent of the overall vote to Cassidy's 41 percent.
"Tonight, 60 percent of the people in Louisiana have voted for change," Cassidy told supporters Tuesday night.
Cassidy was helped by the Republican wave sweeping the country in the mid-term elections, propelling the GOP to majorities in both the House and Senate.
"Bill Cassidy very effectively rode that wave in Louisiana," said Mike Sherman, a Tulane University political analyst.
However, Sherman points out that Louisiana has been trending Republican, leaving Landrieu as the last statewide elected Democrat.
The Saturday runoff on Dec. 6 provides a different dynamic than a Tuesday election.
"What Mary Landrieu's got to do is bring this back to a Louisiana election," Sherman said.
On Wednesday, Landrieu tried to change the subject, playing up her support for the sprawling medical complex under construction in New Orleans' Mid-City and hurricane relief for storm victims.
In Laplace, flanked by four constituents, Landrieu blasted Cassidy for voting against a Hurricane Sandy relief package in the U.S. House, which she said provided $100 million in benefits to Hurricane Isaac victims in Louisiana.
Cassidy sided with critics of the bill, who argued that the spending should be offset by cuts in other federal programs given the country's mounting debt.
"Bill Cassidy was nowhere," Landrieu said. "In fact, I'm here to say, 'where was Bill when this neighborhood went underwater?'"
Cassidy scheduled no public events on the first day of the runoff campaign.