Six in 10 Americans say the government should not regulate whether gays and lesbians can marry the people they choose, a survey finds.

As same-sex couples line up to get marriage licenses in California on June 17, the USA TODAY/Gallup Poll found that 63% of adults say same-sex marriage is "strictly a private decision" between two people.

That the government has the right "to prohibit or allow" such marriages was stated by 33%, and 4% had no opinion.

QUESTION OF THE WEEK: Does it matter to you whom your neighbor marries?

On Monday, the California secretary of state said an initiative to amend the state Constitution to define marriage as a union "between a man and a woman" will be on the ballot Nov. 4. If it passes, it would overturn a state Supreme Court ruling in May that legalized same-sex marriage. After Massachusetts legalized same-sex marriage in 2004, 11 states voted on similar questions.

"Those initiatives … did have an impact in election results," says Mark Rozell, professor of public policy at George Mason University in Fairfax, Va. "Turnout was 2.4% higher on average in those 11 states than the other 39 states."

But these poll findings "suggest caution" to conservative activists who think this will mobilize voters, he says. "People were warned, with lots of overheated rhetoric, about the consequences of gay marriage in Massachusetts. They didn't see it affect their own lives. Now, most people have let loose a collective yawn about the issue."

Poll findings:

A majority of respondents at every level of education and income say same-sex marriage is "strictly private." This was true:

• In every region: East (71%), West (64%), Midwest (63%) and South (56%).

• Among all ages except "65 and older": 18 to 29 (79%), 30 to 49 (65%), 50 to 64% (62%) and 65 and older (44%).

• Among people who also say they have a favorable view of any of the three leading presidential candidates. For those holding favorable views for John McCain, 55% say marriage is a private decision; for Barack Obama, 75% say so; and for Hillary Clinton, 69% do. All three oppose same-sex marriage. Both Democrats both favor civil unions.

• Among people who say a relative, friend or co-worker personally has told them he or she was gay or lesbian (73%).

The strongest support for government regulation of same-sex marriage came from people who say they:

• Attend religious services weekly (56%).

• Are Republicans (56%).

• Are politically conservative (54%).

"After Massachusetts, the public has seen that the decision there has not affected people's lives as much as was feared," Rozell says.

Still, there are forms of marriage Americans overwhelmingly do want to see regulated: 66% say polygamy should not be a strictly private decision; 78% say the government should regulate marriages involving someone under 16.

Every state but one, New Hampshire, requires parental permission to marry someone under 18, according to the National Conference of State Legislatures. New Hampshire sets the age at 17. Mississippi sets it at 21.

Enlarge By Kimberly White, Reuters Afi Wikins, left, and her partner Quesha Landers make their appointment for a marriage license at city hall in San Francisco, Calif.