Social and religious conservatives are placing an increasingly large wager on a strategy they believe could overcome their constituents' lack of enthusiasm for Sen. John McCain, giving him a competitive edge over Sen. Barack Obama.

The strategy is a reprise of one Karl Rove used to push George W. Bush to victory in 2004, when he helped place measures banning same-sex marriage on the ballot in 11 key states. The Republican incumbent carried them all as religious conservatives — particularly evangelical Protestants — flocked to the polls to support the initiatives. This time, similar measures denying marriage to gay and lesbian couples will be on the ballot in California, Florida and Arizona.

The Family Research Council believes that McCain could win in California. "It's been a long time since California was in play for a Republican," said David Nammo, who directs the council's legislative efforts. His optimism is based on a private survey in which 58 percent of all likely voters said they "would be more likely to support a presidential candidate" who favors banning same-sex marriage.

McCain supports the proposed amendment to the California constitution forbidding same-sex marriage; Obama opposes it.

This time, however, religious and social conservatives aren't banking on opposition to gay marriage alone. Across the country, nearly 100 statewide questions have qualified for the ballot in the November election. As many as 60 could be added. Many of these involve social questions about which ideological and religious conservatives have strong feelings.

Colorado — a pivotal swing state — has two. One would define the moment of conception as life's legal beginning; the other would end affirmative action in college admissions and government hiring. South Dakota will consider banning abortion except in cases of rape, incest or threats to the mother's health. California will vote on parental notification in abortion cases. Arizona will weigh a proposal to deprive employers who hire illegal immigrants of their business licenses. Missouri will decide whether to make English its official language.

Some conservative strategists believe that ostensibly liberal measures to legalize stem cell research in Michigan and to permit assisted suicide in Washington state ultimately will also work to the Republicans' advantage — again by drawing to the polls social conservatives who wouldn't necessarily turn out just to support McCain.

To a large extent, Republicans are being encouraged to rely on this sort of state-by-state strategy because they see the election shaping up as less a contest between Obama and McCain and more as a kind of referendum on the presumptive Democratic nominee, his character and fitness for office. If they're right, Obama would face a larger-than-expected number of voters likely to take a skeptical view of his credentials.

Ballot propositions involving hot-button social issues not only are likely to turn out evangelical voters in large numbers, they might force Obama to take specific positions on the issues as he campaigns across the country. If he's forced to declare himself on when life begins or on assisted suicide, he risks alienating either the left wing of his own party or the faith-formed voters his campaign has spent so much time courting.

Still, a couple of this election season's strongest trends are working in Obama's favor. One is the overwhelming support the Illinois senator enjoys among one of the electorate's most important emerging constituencies — Hispanics. According to a nationwide survey conducted last week by the nonpartisan Pew Hispanic Center, registered Hispanic voters favor Obama over McCain 66 percent to 23 percent. Like other registered voters, Hispanics are far more worried about economic issues than they are about immigration reform or the war in Iraq.

At the same time, surveys of all voters find that economic anxieties are strong among this election's other emergent (and pro-Obama) constituency: voters younger than 30.

So, in key states across the country, this election might come down to a contest between the economic voters' dissatisfaction and the values voters' old-time political religion.

Tim Rutten is a Los Angeles Times columnist. Reach him at timothy.rutten@latimes.com.