How much sway do past Democratic nominees have? Unless you're Barack Obama, not much.

Once they won the Democratic presidential nomination. But do their endorsements matter now?

Unless your name is Barack Obama, not really.

A national USA TODAY/Suffolk Poll asked likely Democratic voters whom among the party's past presidential nominees would have the most influence on their vote today. Two-thirds named former president Obama, who moved out of the White House almost three years ago.

Obama hasn't endorsed anyone so far, including his former vice president, Joe Biden.

Kate Pritchard, 63, a retired teacher from Durango, Colorado, is supporting New Jersey Sen. Cory...