One mother said it was the violence. Another said it was the drug dealing. A third said it was the growing number of children she noticed each day smoking, hugging and kissing in the schoolyard. One by one, two dozen parents from low-income neighborhoods here in southwest Albuquerque explained how fear and anguish had led them to remove their children from public schools and enroll them in private schools costing as much as $2,000 a year. Their stories unfolded as part of a plea to lawmakers to enact a school voucher program that would let them use public funds to help pay private school tuition. It is a plea that has caught the ear of Republicans here, particularly Gov. Gary E. Johnson, who is proposing what would be the most ambitious voucher program in the country. But the parents' heartfelt passion is being met with equal fervor by other politicians, as well as teachers and their union representatives, who fear that taking money out of public schools would hasten their erosion. It is a debate playing out across the country with increasing intensity as more than 25 legislatures consider bills that would create some type of system in which public dollars would be used for private and parochial schools like the Abundant Life Christian School here, where many parents pay $2,000 a year for each child they enroll. Even with violence, drugs, crowding and unqualified teachers undermining achievement in many public schools, few measures, if any, including New Mexico's, are expected to pass this year. But forces on both sides -- and experts who have studied the public and private financing of education -- say support for school vouchers is growing so rapidly, especially in poor neighborhoods, that more cities and states will eventually implement programs through legislation or statewide ballot initiatives. ''A lot of people have been talking about this issue for quite a few years,'' said Eric Hirsch, a senior policy specialist for the National Conference of State Legislatures, who tracks education issues. ''A lot of states aren't quite there yet, but there are a lot of proposals out there.'' Paul Peterson, a professor of government at Harvard who has studied the existing programs, said the growing popularity of charter schools around the country was strong evidence that more voucher programs were inevitable. Charter schools are public schools that operate largely free of state and local regulations and unions. They are intended to provide a creative alternative to traditional public schools but must demonstrate progress or risk being closed. ''Every time something is introduced that provides more choice, it is never taken away,'' Professor Peterson said. ''Parents really like it, so politicians can't afford to take it back. Vouchers may creep along because the political opposition is so intense, but it'll happen.'' Only five public voucher programs are operating now -- in Milwaukee, Cleveland, Florida, Minnesota and Arizona -- each serving a relatively small percentage of children. Here in New Mexico, legislation proposed last year and again this month by Governor Johnson, a Republican in his second term, would exceed those programs significantly by offering each of the state's 316,000 children in public schools a voucher worth $3,500 a year that could be used for tuition at any private or parochial school in the state. ''You would like to have a choice,'' said Geri Paiz, a disgruntled mother who pulled the last three of her six children out of public schools this year and is now paying $1,000 each for them to attend Catholic schools. ''What they don't realize is that many parents would jump at the chance to have a choice.'' For now, the slow pace of acceptance is largely owing to efforts of politically active and well-organized opponents, including unions like the National Education Association and the American Federation of Teachers, which have strong ties to the Democratic Party. The opponents contend that using public dollars to help some students get into private schools hurts those left behind by taking money away from teacher salaries, school construction and teaching materials. They also argue that private and parochial schools, which have the right to accept or reject applicants, would take only higher-performing children, leaving public-school classrooms filled with a higher percentage of students with learning, language and behavioral problems. Independent studies of the Milwaukee and Cleveland programs have found that students who use vouchers to attend private schools perform at a slightly higher rate than public-school students. A greater advantage, as the studies show, may be satisfaction among parents -- for having the choice and for feeling secure that their children are learning in a safer environment. But researchers like Kim Metcalf, a professor of education at Indiana University, say the programs are too young and too small to draw any definite conclusions, and some results may reflect factors that have little to do with the classroom. ''If you look at the performance of kids in private versus public schools, the private schools look substantially better,'' Mr. Metcalf said. ''But there's a probability that private-school parents are better-educated, make more money and provide more intellectual stimulus at home.'' Mr. Peterson said, ''Nobody finds them bad for kids, and there is a tremendous enthusiasm from parents.''