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Melinda Deslatte, Associated Press
In this Aug, 20, 2014 file photo, U.S. Rep. Bill Cassidy, a Republican, speaks to reporters after qualifying to run for the U.S. Senate in Baton Rouge, La. A handful of tight races in states with quirky election laws make for the headache-inducing possibility that Election Day will come and go without a deciding which party controls the U.S. Senate. And if that happens, brace for a fierce runoff election and possible recounts that could make for an ugly holiday season in politics and government.

WASHINGTON — A suspenseful election night is one thing. But what if it stretches out for a month or more?

A few tight races in states with quirky election laws make it possible that voters on Election Day won't decide which party controls the Senate.

Louisiana's election laws are a chief reason. Strategists expect a Dec. 6 runoff.

They say Democratic Sen. Mary Landrieu and top Republican challenger Bill Cassidy will struggle to exceed 50 percent on the crowded, all-candidates Nov. 4 ballot.

Control of the Senate could hang on a Louisiana runoff.

Republicans need six more seats to rule the chamber. Several possible scenarios get them to five pickups without Louisiana.

The possibility of a Georgia runoff and a late vote count in Alaska could further complicate the outcome.