Have Dems ever won w/ a candidate who started his race polling behind the GOPer? [View All]

[OzarkDem]

Most recent Dem candidates begin a presidential campaign ahead of their GOP opponent, then fight to keep from losing that always-shrinking advantage before November. The wider the margin of approval over the GOP candidate, the more "cushion" the Dem candidate has to withstand the withering negative attacks from the news media and the GOP.

Can someone explain how fielding a candidate who is "less popular" than their GOP candidate is going to work? Has there ever been a time in Dem history when a Dem candidate (not an incumbent) has begun a campaign behind the GOP'er and been able to win?