Rep. Bill Cassidy (R-La.) (U.S. House of Representatives) Rep. Bill Cassidy (R-La.) (U.S. House Web site)

Rep. Bill Cassidy (R-La.) is running for Senate in 2014, the AP reports. Cassidy will challenge Sen. Mary Landrieu (D), a top Republican target.

In three elections, Landrieu has never won more than 52 percent of the vote, and President Obama lost Louisiana by over 17 points last fall.