traveled from delaware to washington this weekend for a secret meeting with influential liberal senator elizabeth warren. >> she's the leading voice. i'm not surprised they will seek her counsel. >> reporter: the massachusetts senator has refused to endorse front didn frontrunnerner hillary clinton. >> i want to see all of the presidential candidates lay out where they stand on key issues. >> reporter: biden associates see a possible opening because clinton has been battling a trust issue. >> did you wipe the server? >> with a cloth or something? >> reporter: the latest orc poll shows 53% have an unfavorable opinion of clinton while 44% view biden that way. bernie sanders sees clinton's numbers as helping him. >> where he gaining. what the polls seem to indicate is that hillary clinton support seems to be receding.