Louisiana Senate Race Heads To A Runoff

The race between Sen. Mary Landrieu (D-La.) and Republican Bill Cassidy was projected to go to a runoff by ABC and NBC on Tuesday.

Landrieu, the incumbent, has served three terms representing Louisiana in the U.S. Senate. Landrieu was among Democrats hammered for aligning with President Barack Obama while vying for support in a red state. The senator held her ground, saying she was "not backing up" from Obama in a debate the week before the election.

Landrieu's most fortuitous challenger, Rep. Bill Cassidy (R-La.), represents Louisiana's 6th District in the U.S. House. Cassidy served on the Louisiana state Senate until he was elected to the U.S. House in 2008.

Nine candidates were on the ballot in Louisiana, one of three states to operate under a top-two system. Also known as a "blanket primary," the voting format allows all primary candidates to challenge the incumbent in the general election. If no candidate receives more than 50 percent of the vote, the top two candidates face off in a runoff election at a later date.

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