President Bush is winding up the 1990 campaign season trying to exact revenge on Ann Richards, the state treasurer who held him up to public ridicule at the 1988 Democratic Convention.

Bush devoted Monday to campaigning across Texas on behalf of Clayton Williams, Richards' Republican foe in Tuesday's gubernatorial election. The president addressed rallies in Tyler, Waco and Houston, the final stops on his six-day, cross-country swing.Richards drew knee-slapping laughter at the Democratic National Convention in San Francisco when she described Bush as a stumbling aristocrat. "He can't help it. He was born with a silver foot in his mouth," Richards declared.

Bush, who has taken a number of swipes at Richards since, told a news conference in Orlando, Fla., last week: "I'm strongly in favor of Clayton Williams over his opponent - not just for personal reasons."