All year long, Hillary Clinton has proclaimed her strong position atop the field.
That position appears to be slipping.
From October 4 to October 9, Clinton saw her support tumble from 51 percent of Democratic support to just 41 percent.
Her nearest competitors, Vermont Senator Sanders and Vice President of the U.S. Joe Biden, who has yet to decide whether he will run, both made gains. Support for Sanders jumped from just over 24 percent to 28 percent, and Biden rose from 16 percent to a even 20 percent in the same time period.If she has a poor performance Tuesday, will Democrats keep believing she's their leader?