BURLINGTON, Vt. (AP) - President Barack Obama could be caught in an election-year bind on gay marriage, wedged between the pressure of supporters who want him to back same-sex marriage and the political perils of

igniting an explosive social issue in the midst of the campaign.
    
Interviews with gay rights advocates and people close to Obama's campaign suggest it is no longer a matter of if, but when the president publicly voices his support for gay marriage.

But Obama backers are split over whether that will happen before the November election.
    
Gay marriage is already a big issue in Maine, where Obama is headlining two fundraisers on Friday.

The president also is attending fundraisers in Vermont, where gay marriage is legal.
    
Obama once opposed gay marriage but now says his views are "evolving."