CHILDREN have always served as convenient props for political candidates: Kiss a baby. Hug a toddler in a day-care center. Visit a school. Child advocates call this the kiss-and-run approach, since these photo ops rarely translate into policies that benefit children.Now that may be changing. If children's advocacy groups across the United States have their way, politicians will be forced to deliver more than rhetoric to the 64 million youngest Americans who have no political voice and no vote. Tired of elected officials who give little more than lip service to families, groups in at least 15 states - among them Florida, Texas, California, Illinois, New York, Maryland, and Michigan - are launching sophisticated campaigns to hold candidates accountable for making chil dren more than symbols. In Florida, this week marks the beginning of a statewide children's campaign called "Vote Kids '92." Organized by the non-profit Florida Center for Children and Youth in Tallahassee, the year-long program features a three-tiered effort. First, it will educate candidates about the needs of children. Trained volunteers - part of what director Jack Levine calls "an army of advocates will interview candidates to determine their level of interest in children. Second, through public service announcements, guest columns, and newsletters, the group will use "an arsenal of information" to increase public awareness of "the real needs of real parents," such as health care, safe child care, accessible education, and pro-family workplace policies. They will also emphasize the services children lack. Finally, the campaign will register new voters who are concerned about children. It seeks to turn schools, day-care centers, clinics, hospitals - any place where parents and children regularly go - into standing voter registration sites. Levine sees election laws as antifamily, because polling booths are open from 7 a.m. to 7 p.m. on a workday. "On a typical Tuesday at 7 in the morning, the parents I know, and I'm one, are busy matching socks, packing lunch boxes, strapping children into car seats, and getting on their way for the day," he says. "The idea of taking a detour to vote on a school day is simply inconvenient for most parents. And at the end of the day, when we're most rushed as parents, we are driving into a convenience store for milk instead of driving into a polling place for votes." As one solution, volunteers hope to make it pos sible for child-care centers to stay open an extra hour on election days "to allow parents the opportunity to be both a responsible citizen and a responsible parent." Too often, advocates explain, adults fail to understand that they are children's proxies at the ballot box. That attitude may be changing in San Francisco, where residents are voting today on a Children's Amendment. Proposition J, as the measure is called, will allocate 2.5 percent of property-tax revenues for child care, health care, and other services for children. It will also prevent cuts in children's services for 10 years. If the amendment passes - and supporters are optimistic that it will - San F rancisco will become the first city to guarantee funds for children in its charter. Tireless advocates like Levine and others have experienced enough defeats to know that these latest campaigns won't be easy. But they are driven by troubling statistics: One in five American children lives in poverty. One child in five has no health insurance. One child in four will not graduate from high school. One child in 12 will be born to an unmarried teenage mother. These visible and urgent problems are regularly gasped at without being systematically addressed by politicians. Susan Bales, a child advocate in Washington, D.C., explains the challenge: "We've seen amazing response to an elderly agenda. People understand that it includes Medicare, Social Security, and long-term care. But if you say, 'What is a children's agenda?' they look at you bewildered. We're trying to posit that it's health, education, safety, and security for all American children." To acknowledge these goals is to recognize the responsibility of legislators and voters. That step is long overdue in a nation where increasingly complicated family matters have been left too carelessly to the beleaguered family.