Who do you think will pose a greater long term threat to Hillary Clinton's status as a front-runner; Bernie Sanders or Joe Biden? (Assume, for the sake of the poll, that Biden decides to run)
Bernie Sanders is not a serious challenger. He has no appeal beyond the fringe of the Democratic Party. Joe Biden is an establishment Democrat who could give Clinton a real run for her money.
Sanders as a presidential candidate poses a greater threat. However it wouldn't surprise me if Biden had some dirt on Hillary he could use against her.
Sorry to all the Bernie folk, but he really has no shot at all.