Since the primary, Landrieu has undergone a series of humiliations. First, the Democratic Senatorial Campaign Committee announced it would not spend any money supporting her in the runoff. Landrieu's campaign was already practically broke, and in the weeks following the primary more than 90 percent of the television ads Louisiana voters saw were from Cassidy or groups supporting him.

Then, in a last-ditch attempt to demonstrate her clout in the Senate, Landrieu—who describes herself as "a strong supporter of the oil and gas industry"—persuaded Harry Reid, the outgoing Senate majority leader, to hold a vote on a bill to build the Keystone XL oil pipeline. She spent several days pleading with her Democratic colleagues to vote for it. On November 18, every Republican and 14 Democratic senators supported the bill. It fell short by a single vote. "FAIL MARY," declared a Politico headline.

Now, no one gives Landrieu much of a chance. "She's going to lose—it's just a matter of how much," Bernie Pinsonat, a pollster who works for both Republicans and Democrats, tells me. (Pinsonat began as a Democratic pollster, but that is no longer much of a viable occupation in this state.) Elliott Stonecipher, a Shreveport-based political analyst, adds: "She'll have trouble doing better than the 42 percent she got in the primary, and it could be worse than that." Many observers question Landrieu's campaign strategy, from her muddled message to the way she has allocated her funds. But, says Bob Mann, a former Democratic staffer who now writes a newspaper column and teaches at Louisiana State University, "She could be the best swimmer in the world, and it wouldn't matter. The tide is just too strong."

Still, Landrieu must go through the motions. She must play out the string. "I am fighting hard until the end," she announces in Hammond, surrounded by several local mayors and state legislators and a couple of dozen supporters. December in Louisiana: sunny and 80 degrees. Outside the canopy, a man and a woman with six platinum-blond children are waving a sign that says, "Babies are a blessing. Choose life." They are handing out pro-Cassidy literature. On the other side of the canopy, a woman is holding a Sierra Club sign that says, "Keep the Frack Out of My Water." (Landrieu is pro-fracking.)

Landrieu approaches a pair of grandmotherly women in Democratic Party T-shirts and puts her arm around one of them. They've been making phone calls on her behalf, and she wants to know if the word is getting out—are people starting to see that this race isn't about the national parties, but about the local matters Landrieu wants it to be about? Has anything changed since the primary?

"I haven't seen any change," says Jeanne Voorhees, a 72-year-old with a cross necklace. Bernadette Powell, who is 68 and moved to this part of the state when she lost her New Orleans house in Hurricane Katrina, tells Landrieu she thinks she spent too much time in this week's debate haranguing Cassidy about a late-breaking scandal involving his Louisiana State paycheck.