U.S. Sen. Mary Landrieu (D-LA) speaks during a campaign event in New Orleans, Louisiana November 1, 2014. Reuters/Jonathan Bachman

Louisiana Democratic incumbent Sen. Mary Landrieu was expected to come out on top of the Senate open primary on Tuesday, paving the way for a Dec. 6 runoff against top Republican challenger Rep. Bill Cassidy. Landrieu had to win more than 50 percent of the vote to win outright.

Landrieu defended her Senate seat against seven candidates, including Rob Maness, a tea party candidate who pulled 15 percent of the vote in the latest poll over the weekend by Public Policy Polling. Roughly 43 percent said they’d vote for Landrieu. While Landrieu showed strong leading up to the open primary, she trailed Cassidy in runoff situations in polls taken in recent weeks. Cassidy polled between four and eight percent ahead of Landrieu between Oct. 16 and Oct. 30 in runoff situations, according to Real Clear Politics.

The 18-year senator was outspoken about her confidence in outright victory on Tuesday and even refused to book television ad time after the open primary. A close race wouldn’t be anything new for Landrieu, who is jokingly referred to as “Landslide Landrieu” because of her history of tight races. She received strong support from former Secretary of State Hillary Clinton.

Cassidy was elected to the U.S. House of Representatives in 2008 and has served there since. He served in the Louisiana Senate before that. He is considered a “rank-and-file” Republican according to GovTrack’s evaluation of his Congressional voting record. He opposed the February 2014 debt extension, Hurricane Sandy recovery funding and an extension of the Violence Against Women Act as a House Representative. He said he was concerned the VAWA could discriminate against religious organizations, which was a common complaint among conservatives.

Maness is a 57-year-old retired Air Force Colonel. Maness is considered a “wildcard” that pulled far-right votes from Cassidy. He’s been critical of both Landrieu and Cassidy during his race, accusing the latter of having no “principles” for voting in favor of continuing funding for the federal government, which funded the fight against the Islamic State group, health care reform and the like.

Republicans spent $2 million more than Democrats in the race: $23.4 million and $21.2 million, respectively, according to Smart Media Group.