President Obama announces support for building an oil pipeline from Oklahoma to Texas, Thursday in Cushing, Okla. Tom Pennington/Getty Images hide caption

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A driver pumps gas into his Toyota Prius hybrid at a gas station in Sunnyvale, Calif., in 2007. Paul Sakuma/AP hide caption

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Peoria, Ill., as seen from across the Illinois River. Jeff Haynes/Reuters /Landov hide caption

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Sen. Jon Tester, D-Mont., faces a potentially tough re-election bid. Win McNamee/Getty Images hide caption

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Republican presidential candidate Mitt Romney pauses during a visit to St. Paul's Lutheran Church while campaigning in Berlin, N.H., on Dec. 22. Charles Krupa/AP hide caption

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President Obama greets students after speaking at the University of Michigan in Ann Arbor on Jan 27. Young Republicans say they see an opportunity in 2012 to dent Obama's popularity among the youngest voters. Jewel Samad/AFP/Getty Images hide caption

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Former Pennsylvania Sen. Rick Santorum speaks at the Bella Donna Chapel in McKinney, Texas, on Wednesday. Rex C. Curry/Associated Press hide caption

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A Mitt Romney supporter holds up a sign showing her love for Romney and Denver Broncos quarterback Tim Tebow at a rally for the GOP presidential candidate at Arapahoe High School this week in Centennial, Colo. Marc Piscotty/Getty Images hide caption

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Men arrive at a campaign rally for Mitt Romney in Elko, Nev., on Friday. Emmanuel Dunand/AFP/Getty Images hide caption

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