Cathryn, the cases of Bill Bennett and Trent Lott are not truly similar.
Trent Lott had pretty much burned his credibility with true conservatives through years of unnecessary compromise with the opposition. When the wolves of Political Correctness started circling over his remarks at the birthday party, his supply of "good will" from those who once would have backed him was severely depleted. Years of frustration engendered by Lott's kowtowing to the Clinton administration, his sabotage of the impeachment process, the bargaining away of conservative issues and passage of liberal programs, and finally, the unnecessary "power sharing" of the Senate with the opposition and his inability to keep control of Jeffords left him bereft of support when he badly needed it. Lott was not at risk of losing his seat... and the leadship of the Senate Republicans would remain in the hands of a Republican; leaving him twisting in the wind, even when he did not deserve it for the remarks, was understandable given the rest of his actions/inactions.
Bill Bennett has unfortunately played into the hands (hmmmm, interesting way to put it) of those who promote moral relativism. His gambling (whether a problem for him or not) has damaged his, and by association the Republican party's, credibility. Officials in the party and Republican politicians had given him their imprimatur of moral superiority and rectitude by the positions they had given him and by their citation of his works and words; their judgement, rightly or wrongly, is now called into question and WILL be criticized by those pushing relativism. The correctness and value of those ideas and philosophies he espoused in his books are now "damaged goods," open to ad hominem attacks on the messenger. The level of discourse about those ideas has been and will be lowered.
Already we see those on this forum positioning various vices as either equivalent or not-equivalent to gambling. This is just a microcosm of the firestorm of criticism we will see from the Left, as they gleefully jockey to position their favorite vices, criticized by Bennett in his speeches and books, as equivalent or "not as bad" as gambling.
Bill provided a rational, well presented indictment of the dangers of moral relativism and unlimited license and did so from a position that appeared to his readers as the moral "high ground." The criticism he is not receiving from the conservatives most likely has its roots in disappointment in his lost appearance of rectitude and a feeling of betrayal of their expectation that he truly deserved to stand on that "high ground."