Sources tell NPR that former New York City Michael Bloomberg is seriously considering launching an independent bid for the White House. Thibault Camus/AP hide caption

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Bernie Sanders, Hillary Clinton, center, and Martin O'Malley on stage at the Democratic presidential primary debate Saturday at Saint Anselm College in Manchester, N.H. Jim Cole/AP hide caption

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Former Virginia Sen. Jim Webb, accompanied by his wife, Hong Le Webb, announces he will drop out of the Democratic race for president during a news conference at the National Press Club in Washington on Tuesday. Andrew Harnik/AP hide caption

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Secretary of State Hillary Clinton testifies in January 2013 before the Senate Foreign Relations Committee on the attack on the U.S. mission in Benghazi, Libya. Mandel Ngan/AFP/Getty Images hide caption

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Secretary of State Hillary Clinton stands with Libyan fighters who ousted Moammar Gadhafi during an Oct. 18, 2011, visit to Libya. Clinton was a strong supporter of U.S. intervention in Libya. Kevin Lamarque/AFP/Getty Images) hide caption

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On 'Morning Edition': Michele Kelemen reports
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Sen. John Kerry, D-Mass., U.N. Ambassador Susan Rice, and Secretary of State Hillary Clinton listen to President Obama speak at the State Department in May 2011. With Rice withdrawing her name from consideration to succeed Clinton, speculation has turned to Kerry. Chip Somodevilla/Getty Images hide caption

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