Efforts to ban gays and lesbians from adopting children are emerging across the USA as a second front in the culture wars that began during the 2004 elections over same-sex marriage.

Steps to pass laws or secure November ballot initiatives are underway in at least 16 states, adoption, gay rights and conservative groups say. Some - such as Ohio, Georgia and Kentucky - approved constitutional amendments in 2004 banning gay marriage.

"Now that we've defined what marriage is, we need to take that further and say children deserve to be in that relationship," says Greg Quinlan of Ohio's Pro-Family Network, a conservative Christian group.

Florida has banned all gays and lesbians from adopting since 1977, although they can be foster parents. State court challenges and a campaign by entertainer Rosie O'Donnell to overturn the law have failed. A pending bill would allow judges to grant exceptions.

Mississippi bans adoption by gay couples, but gay singles can adopt. Utah prohibits all unmarried couples from adoption.

Kent Markus of the National Center for Adoption Law & Policy in Ohio says he hasn't seen this much activity in 15 years as a researcher.

Richard Carlson, a professor at South Texas College of Law in Houston, says adoption laws based on judgments of morality offer "a weak argument" and will face legal challenges. He cites U.S. Supreme Court rulings striking down bans on interracial marriage and sodomy, which reflected prevailing views when enacted. The high court has not taken up a state ban on gay adoption. (Vote: What do you think about gay adoption?)

Religious groups and state courts are grappling with the issue. Roman Catholic bishops in Massachusetts are seeking an exemption from state anti-bias laws to allow the church to bar gays from adopting through its social service agencies. Meanwhile, a judge in Missouri ruled last week that the state could not deny a foster care license to a lesbian.

Fueling the political activity:

• Ballot victories. Social conservatives view family makeup as the next battleground after passing marriage amendments in 11 states in 2004. They welcomed a bill introduced this month in Ohio that would ban gays and lesbians from adopting or raising foster children. They vow to put it on the ballot if the bill fails.

Patrick Guerriero of Log Cabin Republicans, a gay political group opposed to marriage and adoption limits, calls the strategy the next step by conservatives.

• Election-year politics. Republicans battered by questions over ethics and Iraq "might well" use the adoption issue to deflect attention and draw out conservatives in close Senate and governor races in states such as Missouri and Ohio, says Sherry Bebitch Jeffe, University of Southern California political scientist.

The aim is to replicate 2004, says Julie Brueggemann of the gay rights group PROMO: Personal Rights of Missourians. She says marriage initiatives mobilized conservative voters in 2004 and helped President Bush win in closely contested states such as Ohio. Republicans "see this as a get-out-the-vote tactic."

Republican pollster Whit Ayres is skeptical. Adoption, he says, "doesn't have the emotional power of the gay marriage issue because there is no such thing as the phrase 'the sanctity of adoption.' "

Commentary: