Vice President Joe Biden announces he will not seek the 2016 Democratic presidential nomination during an appearance in the White House Rose Garden with President Obama and Dr. Jill Biden. Carlos Barria/Reuters/Landov hide caption

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Vice President Biden talks to a woman in biker gear, who's sitting on a chair in front of him at a diner in Ohio in September 2012. She's not sitting on his lap, but it sure looks like it. Carolyn Kaster/AP hide caption

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Vice President Joe Biden is still contemplating getting into the presidential race, but he's getting a nudge with an ad from a group supporting him. Bernat Armangue/AP hide caption

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Nobody really knows whether Vice President Biden will run, but there's a debate in Democratic circles about whether he can afford to wait. Chip Somodevilla/Getty Images hide caption

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Supporters of Democratic presidential candidate Hillary Clinton cheer as she arrives at the state's annual Democratic convention Saturday in Manchester, N.H. Jim Cole/AP hide caption

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A man carries a cardboard cutout of Hillary Clinton in Des Moines, Iowa. Clinton and other traditional candidates have struggled to breakthrough as outsiders have captured the attention this summer. Charlie Neibergall/AP hide caption

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Hillary Clinton speaks at the Democratic National Committee's summer meeting in Minneapolis, where she was trying to court all-important party delegates to her side. Jim Mone/AP hide caption

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President Obama has stayed neutral in the race to replace him, but as rumors swirl that Vice President Biden could jump in, a White House spokesman said Monday it's possible Obama will endorse. Saul Loeb/AFP/Getty Images hide caption

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Sen. Ted Cruz, R-Texas, apologized Wednesday after making a joke about Joe Biden while the vice president was mourning the death of his son. Charles Dharapak/Associated Press hide caption

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Vice President Biden and House Speaker John Boehner wait for President Obama's State of the Union address in front of a joint session of Congress in 2012. As vice president, Biden is also leader of the U.S. Senate, but only gets a vote when senators are evenly divided. Saul Loeb/AP hide caption

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