FILE - In this May 3, 2012 file photo, U.S. Senate candidate Republican Ted Cruz participates in a live debate at the University of Houston in Houston. Former presidential candidate Rick Santorum endorsed Cruz in Texas' crowded race for a U.S. Senate seat on Thursday, saying the firebrand attorney and tea party favorite “has the wow factor.”
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Texas Republican primary candidate for the U.S. Senate Craig James makes a point during a press conference Thursday, May 24, 2012, in Houston. Also vying for the party’s nomination are Lt. Gov. David Dewhurst, ex-Dallas Mayor Tom Leppert and Ted Cruz.
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President Barack Obama, left, tours TPI Composites, a manufacturer of wind turbines blades, with plant manager Mark Parriott, Thursday, May 24, 2012 in Newton, Iowa. In Obama’s second visit as president to Newton, a city of about 15,000 east of Des Moines, he argued for Congress to renew wind energy tax credits.
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President Barack Obama speaks during a campaign rally at the Paul R. Knapp Animal learning center, Thursday, May 24, 2012 in Des Moines, Iowa.
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President Barack Obama greets supporter at a campaign rally at the Paul R. Knapp Animal learning center, Thursday, May 24, 2012 in Des Moines, Iowa.
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President Barack Obama greets supporter at a campaign rally at the Paul R. Knapp Animal learning center, Thursday, May 24, 2012 in Des Moines, Iowa.
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President Barack Obama, center, greets a young supporter during a campaign rally at the Paul R. Knapp Animal learning center, Thursday, May 24, 2012 in Des Moines, Iowa.
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FILE - In this Nov. 29, 2008 file photo, then-Sen. Ted Stevens, R-Alaska, leaves the Senate chamber after making his last formal speech on the Senate floor. The Justice Department's internal ethics watchdog on Thursday, May 24, 2012 said that two prosecutors in the bungled corruption case against Stevens engaged in reckless professional misconduct by failing to disclose information favorable to the lawmaker, who eight days after his 2008 conviction lost re-election to the seat he held for 40 years. The Office of Professional Responsibility, however, did not find that the misconduct was intentional.
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President Barack Obama, right, is greeted by Col. Jennifer Walter, center, Vice Wing Commander, Iowa Air National Guard and Lt. Col. Shawn Ford, Operation Group Commander, Iowa Air National Guard Base, upon his arrival at Des Moines International Airport, Thursday, May 24, 2012, in Des Moines, Iowa.
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In this photo taken May 24, 2012, Sen. Marco Rubio, R-Fla. has a conversation just off the Senate floor on Capitol Hill in Washington. Rubio is planning a swing-state summer bus tour that will also roll through South Carolina, the early presidential primary battleground.
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Graphic shows Iowa’s past presidential winners, demographics and jobless rate
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President Barack Obama arrives at Des Moines International Airport, Thursday, May 24, 2012.
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In this photo taken May 24, 2012, Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks at a school in Philadelphia. When Romney decried Barack Obama as beholden to the nation’s teachers’ unions and unable to stand up for reform, he glossed over four years of a relationship that has been anything but cozy.
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FILE - In this April 24, 2012 file photo, President Barack Obama pauses as he speaks at the University of North Carolina at Chapel Hill. The Senate has rejected Democratic and Republican plans for averting a doubling of interest rates on federal college loans for 7.4 million students.
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FILE - This March 24, 2012 file photo shows the United States Supreme Court in Washington. The Court ruled unanimously Thursday that three families cannot sue a mortgage company for allegedly charging them a loan discount fee without giving them a lower interest rate.
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A Pakistani man selling cold drinks pushes his bicycle between oil tankers, which were used to transport NATO fuel supplies to Afghanistan, in a compound in Karachi, Pakistan, Thursday, May 24, 2012.
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Republican presidential candidate, former Massachusetts Gov. Mitt Romney, takes part in the 6th grade language arts class during a tour of the Universal Bluford Charter School, Thursday, May 24, 2012, in Philadelphia.
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Republican presidential candidate, former Massachusetts Gov. Mitt Romney, center, is joined by the Universal Bluford Charter School founder Kenneth Gamble, left, and Evie Mcniff, during a round table discussion at the school, Thursday, May 24, 2012, in Philadelphia.
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Republican presidential candidate, former Massachusetts Gov. Mitt Romney participates in a round table discussion at the Universal Bluford Charter School, Thursday, May 24, 2012, in Philadelphia.
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FILE - In this April 25, 2012 file photo, President Barack Obama arrives to speak at the University of Iowa in Iowa City, Iowa. The Iowa magic that launched Barack Obama to the presidency four years ago has all but faded. Today, the Democrat who emerged Cinderella-like in Iowa in 2008 is sharply attacking Republican challenger Mitt Romney’s economic credentials and his ability to grasp voters’ everyday concerns.
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FILE - In this Jan. 3, 2012 file photo, Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks in Des Moines, Iowa. The Iowa magic that launched Barack Obama to the presidency four years ago has all but faded. Today, the Democrat who emerged Cinderella-like in Iowa in 2008 is sharply attacking Republican challenger Mitt Romney’s economic credentials and his ability to grasp voters’ everyday concerns.
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Republican presidential candidate, former Massachusetts Gov. Mitt Romney talks with Salina Beattie during a tour of the 6th grade language arts class at the Universal Bluford Charter School, Thursday, May 24, 2012, in Philadelphia.
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Republican presidential candidate, former Massachusetts Gov. Mitt Romney, and Salina Beattie display class work they did together in the 6th grade language arts class during Romney's tour of the Universal Bluford Charter School, Thursday, May 24, 2012, in Philadelphia.
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Secretary of State Hillary Rodham Clinton speaks during a news conference at the State Department in Washington, Thursday, May 24, 2012, to discuss the State Department's annual report on human rights.
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Secretary of State Hillary Rodham Clinton gestures during a news conference at the State Department in Washington, Thursday, May 24, 2012, to discuss the State Department's annual report on human rights.
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