Put it all together, and you start to get a picture of what a Clinton challenger might look like: probably male, moderate and anti-establishment.

Who matches that profile?

Webb, for one. He has been both a Democrat and Republican. Maybe Brian Schweitzer, the former Montana governor who mixes liberal and conservative positions and is not a fan of the Washington, D.C., establishment. A candidate like Joe Biden, who has been in Washington for over 40 years – probably not.

Meanwhile, more liberal candidates like Dean, Warren and independent Sen. Bernie Sanders of Vermont match the anti-establishment part of the equation. They may, however, be too liberal to take advantage of Clinton’s “weakness” among moderate and conservative voters.