Why didnt Clinton campaigned for Gore

[All Along The Watchtower]

A big part of it was personal. The Gores were so disgusted with Bill Clinton over Lewinsky and probably (with good reason) suspected that it was part of a pattern. Tipper in particular detested the man, and certainly didn't like Hillary either. And Al Gore was specifically angry with Clinton over the fact that he lied to his face about the Lewinsky affair--the President, lying to his Vice President. Gore definitely held that against him.

There were other reasons for sure, but you can't underestimate the personal hostility between the Clintons and Gores at the time.