New Mexico is on the verge of becoming the latest state to require girls entering sixth grade to be vaccinated against a sexually transmitting virus that can cause cervical cancer, a spokesman for the governor said Monday.

The state House approved the bill Sunday, and Gov. Bill Richardson will sign it once he receives the legislation, spokesman Gilbert Gallegos said.

"This is an important anti-cancer vaccine, and the governor believes it's imperative for all girls to be protected against cervical cancer," Gallegos said.

He said the bill will go into effect 90 days after it is signed.

Texas is the only state to require the vaccine so far, but other states are considering doing the same. While federal regulators have approved the vaccine, the issue of making it a requirement for girls has been surrounded by controversy.

Merck & Co., the vaccine's maker, said last month that it would suspend a behind-the-scenes lobbying campaign to get states to require it for school-age girls because of pressure from parents and medical groups.

Texas Gov. Rick Perry sidestepped his state's Legislature when he ordered the shots for girls entering the sixth grade there as of September 2008. He has since had to defend his relationship with Merck. The Associated Press reported Perry's chief of staff met with key aides about the vaccine on the same day Merck's political action committee donated money to the governor's campaign.

It wasn't known if Merck had lobbied New Mexico officials.

Virginia lawmakers passed a similar law, which Gov. Timothy M. Kaine has said he would sign. Massachusetts Gov. Deval Patrick's budget proposal calls for providing the vaccine for free to all girls 9 to 18 who want it.

Legislation to require the vaccine or promote it have been introduced in other states as well.

The federal government approved Gardasil, a three-dose vaccine that protects against the human papilloma virus, or HPV, in June for females ages 9 to 26. The vaccine protects against HPV strains that cause cervical, vulvar and vaginal cancers and genital warts.

More than 500 cases of mostly minor side effects have been reported in girls and women who got the vaccine. Government health officials said last month that no additional warning labels are needed.