DES MOINES, Iowa -- President Barack Obama's support for gay marriage adds a layer of complexity for voters -- especially independents -- in battleground states that will decide the race for the White House.
While the economy is certain to dominate the campaign, gay marriage could have an impact at the margins in key states from Colorado to Ohio to Virginia by influencing voter turnout among important constituencies, including minorities, young voters and evangelicals.
"It may cost you as many votes as it wins you," said Colorado state Sen. Greg Brophy, a Republican.
Advocates on both sides of the emotional issue agree Obama's pronouncement will stoke enthusiasm among core Democrats and Republicans, likely boosting turnout in the November election and fundraising before it. The big unknown is where independent voters land in the fewer than a dozen states expected to make a difference in the quest for the White House. They include Nevada, Ohio, Florida, Virginia, Colorado, Iowa and New Hampshire.
National surveys show most Americans support legalizing gay marriage.
But most blacks -- a core part of Obama's base -- do not. And Obama needs them to turn out in huge numbers to win in battleground states. The same goes for Democratic-leaning Hispanic voters. Most oppose gay marriage.
At the same time, most evangelicals and other conservatives who make up the base of the GOP strongly oppose gay marriage. And Obama's position could end up unifying conservatives behind presumptive GOP nominee Mitt Romney.
North Carolina voters overwhelmingly passed a referendum Tuesday that strengthened the state's gay-marriage ban. It appears to have driven GOP turnout to record levels in a traditionally Republican state that Obama won four years ago.