DES MOINES, Iowa (AP) - President Barack Obama's support for gay marriage adds a new layer of complexity for voters - especially independents - in battleground states that will decide the race for the White House.
    
The economy is certain to dominate the campaign over the next six months.

But 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, among them minorities, young voters and evangelicals.
    
A Colorado Republican, state lawmaker Greg Brophy, says the issue may cost as many votes as it wins.
    
Advocates on both sides of the emotional issue agree that Obama's pronouncement will stoke enthusiasm among core Democrats and Republicans. That's likely to boost turnout in the November election and fundraising ahead of it.