The survey, from GOP firm Magellan Strategies, reveals 51 percent of respondents say it's "time to give a new person a chance" in office. Thirty-nine percent agreed that Landrieu has performed her job well enough to "deserve to be reelected."
Though those numbers are bad news for Landrieu, they're not a clear indication half of Louisiana voters will vote to oust her.
The survey didn't test Landrieu up against her most likely GOP opponent, Rep. Bill Cassidy (R-La.), who has faced criticism from some Republicans for a record they believe isn't conservative enough.
And in a generic ballot test, a generic Democratic candidate keeps the race relatively tight.
Forty-five percent of survey respondents, a plurality, said they'd be voting for a generic Republican, while 39 percent said they'd support the Democrat in the race.
The GOP lead reflects the red tint of the state, which backed Republican Mitt Romney with nearly 60 percent of the vote. But the fact that a generic Democrat so outperforms President Obama in 2012 should be heartening for Democrats.
Democrats have dismissed the Magellan poll as a "push poll," one that seeks to skew the outcome by feeding respondents negative information about the subjects.
While the survey does ask respondents a number of leading questions about Landrieu's record, those questions follow, rather than precede, the generic ballot test — indicating the state's overall sentiment currently tilts in favor of Republicans.
Landrieu is a top Republican target for 2014, but she's weathered some tough reelection fights, and is seen as less vulnerable than some other red-state incumbent senators. The last GOP poll of the race gave Landrieu a five-point lead on Cassidy, while one Democratic poll before that showed her up 10 points.
The Magellan survey was conducted among 1,800 likely Louisiana voters from July 29-30 and has a margin of error of plus or minus 2.3 percentage points.