Former Secretary of State Hillary Rodham Clinton and former President Clinton huddle under an umbrella during inaugural ceremonies for Virginia Gov. Terry McAuliffe in Richmond on Jan. 11. Patrick Semansky/AP hide caption

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The question isn't whether former Secretary of State Hillary Clinton will run for president in 2016 but whether she will stop, say the authors of a new book. Gerald Herbert/AP hide caption

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Then-Secretary of State Hillary Clinton and Vice President Biden at a White House event in October 2011. A new book says President Obama's aides were then studying whether to replace Biden with the former first lady on the 2012 ticket. Kevin Dietsch /UPI /Landov hide caption

itoggle caption Kevin Dietsch /UPI /Landov

George Soros, seen at a forum in Berlin last year, joined a superPAC backing a Hillary Clinton presidential run in 2016. Sean Gallup/Getty Images hide caption

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Hilary Clinton at last week's Clinton Global Initiative forum in in New York City. /PA Photos/Landov hide caption

itoggle caption /PA Photos/Landov

During the 2012 campaign cycle, CNN was among several news networks that hosted Republican debates. Now, the GOP says it doesn't want to be on either that network or NBC. Joe Raedle/Getty Images hide caption

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Former Secretary of State Hillary Clinton appears at the Women in Public Service Project leadership symposium in Bryn Mawr, Pa., on July 9. Matt Rourke/AP hide caption

itoggle caption Matt Rourke/AP