The largest Republican advantage since the Truman administration after World War II.
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The defeat Saturday of Louisiana Democratic Sen. Mary Landrieu was essentially the final act in the Republican Party’s control this fall of the South — a transition expected to have a significant impact on the 2016 White House races.

The victory by Republican challenger and Louisiana Rep. Bill Cassidy means that Democrats in January will be left without a single U.S. senator or governor across nine states — stretching from the Carolinas to Texas.

And GOP runoff victories Saturday in two Louisiana House districts ensure the party of at least 246 seats, the largest Republican advantage since the Truman administration after World War II.