Pipes for Transcanada Corp.'s planned Keystone XL oil pipeline are stacked at a depot in Gascoyne, N.D. The House of Representatives approved the Keystone XL pipeline Friday; the Senate voted against it on Tuesday. Andrew Cullen/Reuters/Landov hide caption

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GOP Rep. Bill Cassidy and Democratic Sen. Mary Landrieu face off in a Dec. 6 Senate runoff. Both are pushing for legislation approving the remaining leg of the Keystone XL pipeline between Alberta, Canada, and Steele City, Neb. Gerald Herbert/AP hide caption

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Sen. Mary Landrieu, D-La., chair of the Senate energy committee, spoke Wednesday about getting congressional approval for the Canada-to-Texas Keystone XL pipeline. With her is Sen. Joe Manchin, D-W.Va., a member of the committee. J. Scott Applewhite/AP hide caption

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Sen. Mary Landrieu, D-La., speaks at an Oct. 2013 news conference on Capitol Hill in Washington. Landrieu's support for the Affordable Care Act is center stage in her campaign for a fourth Senate term. Evan Vucci/AP hide caption

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Sen. Mary Landrieu, D-La., is facing a tough re-election bid. J. Scott Applewhite/AP hide caption

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Rep. Bill Cassidy, R-La. (right), poses with his family and House Speaker John Boehner at the start of the new Congress, on Jan. 3. On Wednesday, Cassidy announced that he would challenge Democratic Sen. Mary Landrieu in 2014. Cliff Owen/AP hide caption

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