Republican Clayton Williams, ahead in the polls in the Texas governor's race, yanked his first and only negative television ad from the airwaves yesterday and urged Democrat Ann Richards to follow suit.

But Richards, the fiery state treasurer who was once introduced by an admirer at a rally as being "tougher than a two-dollar steak," rejected the proposed negative-ad truce. Her aides said the only reason Williams pulled his commercial was because it was inaccurate and easily refutable.

Richards, who survived a nasty primary battle dominated by negative advertising, fired her opening salvo against Williams last week in a TV spot that portrayed the Midland multimillionaire as a businessman mired in debts and lawsuits. In response, Williams broadcast a commercial indirectly linking Richards and the state treasurer's office with the savings and loan scandal. The ad questioned why state deposits were made in some thrift institutions and charged Richards with accepting donations from S&L executives.

Yesterday, Williams campaign chairman Buddy Barfield announced that the ad was being yanked -- sort of. In a letter to Richards, Barfield said that Williams would replace the negative ad with ads "stressing positive aspects of Mr. Williams' candidacy." He then offered Richards "some friendly advice: You need to tell the voters of Texas something positive about yourself. If you continue down the road you yourself have paved, be assured we will answer your attacks in a forceful manner."

But Richards spokesman Bill Cryer said Richards would continue running her ad on Williams the troubled businessman. "We're keeping our ad because it's right. It's a 30-second documentary," he said.

Cryer argued that the Williams campaign pulled its negative ad "because it's wrong." The state did not lose any money in savings and loan deposits, as implied in the Williams ad. And Richards said that none of the S&L executives who have contributed to her campaign were involved in the thrifts where state deposits were placed.