Sen. Mary LandrieuMary LandrieuProject Veritas at risk of losing fundraising license in New York, AG warns You want to recall John McCain? Good luck, it will be impossible CNN producer on new O'Keefe video: Voters are 'stupid,' Trump is 'crazy' MORE (D-La.) leads her closest Republican challenger, Rep. Bill CassidyWilliam (Bill) Morgan CassidyTax bill could fuel push for Medicare, Social Security cuts Collins to vote for GOP tax plan Overnight Tech: Lawmakers want answers on Uber breach | Justices divided in patent case | Tech makes plea for net neutrality on Cyber Monday MORE (La.) by 3 points, according to a new poll, in a key Senate race that may be headed to a runoff.

A CNN/ORC poll released Sunday morning shows 43 percent support for Landrieu and 40 percent for Cassidy. Tea Party candidate Rob Maness was the choice of 9 percent of the respondents.

The telephone survey of 1,013 adults, conducted between Sept. 22 and 25, has a 3-percentage-point margin of error.

The Louisiana race would go to a runoff between the top two vote-getters if no candidate gets more than 50 percent of the vote in November.

Fifty percent of likely voters in the new survey said they would choose Cassidy in that runoff, compared with 47 percent who would pick Landrieu.

Landrieu and Maness each drew 48 percent support in a hypothetical runoff.

President Obama’s approval rating in Louisiana stands at 37 percent in the new poll, compared with 61 percent of likely voters who view him unfavorably.