WASHINGTON, DC - MARCH 22: U.S. Sen. Mary Landrieu (D-LA) (2nd L) talks with a reporter outside the Senate chamber, on Capitol Hill March 22, 2013 in Washington, DC. The Senate is scheduled to vote on amendments to the budget resolution on Friday afternoon and into the evening. (Photo by Drew Angerer/Getty Images)National Journal

To save her Senate seat in Louisiana, Mary Landrieu may secretly be rooting for Republicans to retake the upper chamber.

That might sound counterintuitive, but it's a reality strategists are mulling as they face the growing likelihood that Landrieu won't reach the 50 percent necessary in the November all-party primary to win reelection outright. Under Louisiana's odd election rules, that would mean the race heads into a second round, a Dec. 6 runoff, to determine who wins the closely contested seat.

There's a real chance that Republicans could net five Senate seats before the runoff would take place, making Louisiana's contest the one that decides which party controls the Senate. For Landrieu, that kind of high-stakes runoff could help her mobilize core Democratic constituencies, particularly African-American voters. But it would also turbocharge an already-irritated GOP base, nationalizing the election in a solidly-Republican state.

If Election Day in November puts the Senate firmly in Republican hands, enthusiasm among Louisiana's GOP voters might wane. It also could mean Landrieu's argument that she's a rare moderate voice restraining the excesses of her party resonates more, especially as Republicans recognize their small upper-chamber majority will require Democratic allies to see legislation passed.

"If Republicans have control of the Senate, that will work to her advantage. She can then play even more that she's contrarian to the people in Washington," said Democratic strategist John Rowley, who has extensive experience working on congressional campaigns in Louisiana. "That's what she did in 2002. I can see that being an advantage. To win a race like this, you need to be good, hope your Republican challenger makes an error, and you need some good fortune. That could be her good fortune."

Neither Landrieu's campaign nor the National Republican Senatorial Committee is publicly entertaining the possibility of the race going into overtime, or the likelihood of Louisiana becoming the decisive race in the battle for the Senate majority. Landrieu campaign spokesman Andrew Zucker declared he's confident she'll win 50 percent outright, and won't even need a runoff. "We're just not thinking about that six months out," he said. (She's far from that mark in current polling, and she's needed runoffs to win in two of her last three elections.)

Meanwhile, national Republicans involved in the race aren't eager to call Louisiana clutch either. "It would shock me if it was a determinative race. I either think we win eight-plus seats or 5 or less," said one GOP strategist tracking the campaign.

But strategists with a little less skin in the game aren't so confident. Republican pollster Neil Newhouse floated the possibility of Louisiana being the tie-breaker race at a bipartisan panel sponsored by The Wall Street Journal last Wednesday. "I think you may see 'control of the Senate' messaging used by both R's and D's in late communications to their base voters. Louisiana would be no exception," Newhouse later said.

In 2002, Landrieu faced a similar dynamic. Before November, control of the Senate hung in the balance — and her seat held the prospect of being the majority-maker. But Republicans swept to a majority, and the corresponding runoff didn't draw nearly as much national attention. Landrieu greatly benefited from that dynamic, and without a rallying cry, Republican turnout diminished. After winning only 46 percent of the vote in the November election, Landrieu's share of the vote jumped 6 points, to 52 percent in the corresponding runoff against Republican Suzanne Haik Terrell.

Landrieu, if anything, is sensitive to the changing public mood from a general election to a December runoff. In 2002, to win Republican crossover voters, she aired ads in September that referenced her constructive relationship with George W. Bush. Once Republicans won the Senate, her runoff ads referred to her as a check-and-balance to the Bush administration.

Republican strategist Brad Todd, who is working for Landrieu's leading GOP challenger, Rep. Bill Cassidy, acknowledged that she's been successful when the stakes are lower.

"Mary has succeeded when she can get a race all about Mary," Todd said. "But if the Senate majority rests on Mary Landrieu's election, there is no possible way she is a United States senator in January."

He added the state's strong anti-Obama sentiment this year still makes it harder for her to replicate her 2002 success. Her past reelection campaigns both took place when Bush was in the White House.

Public polling has shown Landrieu among the most vulnerable Democratic incumbents. A Kaiser Family Foundation/New York Times poll conducted in April showed her winning just 42 percent of the vote in an all-party primary, with her approval rating barely above water, at 49 percent. In February, the Democratic firm Hickman Analytics found Cassidy leading Landrieu in a hypothetical runoff, 46 to 42 percent, with her unfavorable rating 10 points higher than her favorable numbers.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.