Like Gore, they were all chosen for their slavish loyalty and limited ability to calculate two and two. Clinton didn't want anybody outshining him. Nor did he want anybody who might have the guts to challenge his corruption.
Consequently, none of these inferiors were capable of running a capable campaign on their own. And Clinton wasn't about to back a bunch of midgets.
He used 'em. Now, he's losin' 'em...