Even with those strengths, Biden's tendency to go off script — in Virginia he called Senate candidate Tim Kaine "Tom Kaine" — causes nervousness among the Obama campaign hierarchy. Transcripts of his remarks are not distributed to the press corps, in contrast to those of the president and first lady Michelle Obama.
Biden knows his fate is tied to Obama.
At an appearance at a campaign office in Iowa this week, he thanked volunteers and reminded them that Iowa was the state that put Obama "on the road" to the presidency in 2008.
"I may have been a little disappointed at the time," Biden said, "but we got the right order."
A supporter shouted, "You're our man in 2016!"
Biden glanced at the woman, but remained uncharacteristically silent.
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EDITOR'S NOTE _ A story about Republican vice presidential candidate Paul Ryan moved previously.
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