Reacting to a furor in public health circles, Merck said Tuesday that it would stop trying to get state legislatures to mandate the use of its new cervical cancer vaccine.

At least 20 states are considering making use of the vaccine mandatory for schoolgirls, and the governor of Texas, Rick Perry, has already done so through an executive order. Part of the state rush to embrace the new vaccine has been fueled by Merck lobbying that began even before federal regulators approved the product last year.

The vaccine is aimed at a sexually transmitted virus that causes cervical cancer. Critics of the vaccine's use on moral and other grounds have used Merck's perceived influence as a weapon to fight its use. And even public health officials who favor the vaccine say the movement to make it mandatory has come too fast, provoking a backlash that could undermine its eventual widespread use.

Merck acknowledged that backlash on Tuesday, saying it would stop lobbying specifically for state mandates. Many of the state proposals have called for requiring girls to be vaccinated before the can enter sixth grade.

Dr. Richard M. Haupt, executive director for medical affairs in Merck's vaccine division, said the company acted after hearing from public health officials and medical organizations that its campaign was counterproductive.

"They believe the timing for the school requirements is not right," Mr. Haupt said.

"Our goal is to prevent cervical cancer," he added. "Our goal is to reach as many females as possible. Right now, school requirements and Merck's involvement in that are being viewed as a distraction to that goal."'

Dr. Haupt said, however, that Merck would continue to provide public health officials and legislators with education about the vaccine and would also continue to lobby for more funding for vaccines in general.

He declined to say how much money or manpower Merck has been expending in its effort to get the cervical cancer vaccine mandated.

The vaccine, called Gardasil, acts against strains of the human papillomavirus that account for an estimated 70 percent of the cases of cervical cancer. The virus, known as HPV, is transmitted sexually, so experts say the vaccine is best given before girls become sexually active.

The vaccine, which costs about $400 for the three-injection regimen, was approved by the Food and Drug Administration last June. A month later a federal advisory panel recommended that girls and women 11 to 26 be vaccinated, although panelists have said that recommendation was not equivalent to recommending mandatory inoculation.

But the speed with which legislatures have moved to mandate the vaccine as a requirement for school entry has galvanized critics. Some say making a vaccine mandatory would pre-empt parental choice, while others argue that protection from a sexually transmitted virus would encourage promiscuity.

Those critics were joined by some worried about the influence of pharmaceutical companies. Merck has been a financial supporter of Women in Government, an national organization of legislators whose members have sponsored some of the state legislation to make the vaccine mandatory.

Yesterday Dr. Larry K. Pickering, the executive secretary of Advisory Committee on Immunization Practices, the federal panel that recommended the vaccine's use last July, applauded Merck's decision to stop lobbying.

"They finally are going to stop doing that, which all of us will be happy about," he said. Dr. Pickering, who works at the federal Centers for Disease Control and Prevention, said that while the vaccine was a useful one, more data on its safety, efficacy and cost were needed before it was made mandatory.

"This is a great vaccine," he said. "It will prevent cervical cancer. But we need to approach it with the approach we take for all vaccines."

He said the backlash against the vaccine could undermine its use. "I think it has been somewhat counterproductive," he said. "Anything that takes away from the process of getting vaccine into people is deleterious to the whole process."