By Nicole Neroulias
SEATTLE (Reuters) - President Barack Obama on Thursday endorsed state ballot initiatives to legalize same-sex marriage in Washington state, Maryland and Maine as he sought to galvanize gay and lesbian enthusiasm for his re-election bid.
Statements issued by the Obama campaign in those three states urging voters to approve the gay-marriage measures on their respective November 6 ballots came five months after Obama became the first U.S. president to express support for the right of same-sex couples to wed.
With polls showing Obama and Republican challenger Mitt Romney running neck and neck, the outcome of the race is likely to hinge largely on the Election Day turnout of their core constituencies, and both candidates are doing the utmost to motivate their supporters.
For Obama, the gay and lesbian community is seen as a loyal and potentially pivotal voting bloc, along with larger demographic groups such as Hispanics and single, young women.
"While the president does not weigh in on every single ballot measure in every state, the president believes in treating everyone fairly and equally, with dignity and respect," according to a statement in Seattle by Paul Bell, press secretary for Obama's campaign in Washington and Oregon.
The state goes on to explicitly urge a yes vote for Washington state Referendum 74, which would allow same-sex couples to marry.
Nearly identical endorsement statements were issued in support of similar initiatives on the November 6 ballot in Maine and Maryland.
Six states and the District of Columbia have already extended marriage rights to gay and lesbian couples, all brought about by court rulings and legislative action.
Maine, which rejected gay marriage in a 2009 referendum by 53 percent to 47 percent, could become the first state to legalize same-sex marriage solely by popular vote.
In Washington state and Maryland, whose legislatures passed laws expanding marriage rights to gay and lesbian couples earlier this year, citizens will vote on whether to let those statutes stand.
Opponents of gay marriage hope Minnesota will become the latest state to pass a constitutional amendment defining marriage as exclusively a union between a man and a woman - effectively banning same-sex nuptials.
Obama previously spoke out against the Minnesota measure.
In Washington state, where polls show the "yes" campaign for gay marriage running ahead of the opposition in a tightening race, campaign manager Zach Silk said in a statement that "having the president weight in on approving Referendum 74 puts an extra gust of wind in our sails."
A recent Washington Post poll found voters in Maryland likely to approve the state's gay marriage law in the November election.
Brian Ellner, co-founder of The Four 2012 campaign, which is fighting for gay marriage rights in Washington, Maryland, Maine and Minnesota, said Obama's support "has had a big impact on public opinion, especially among African-Americans," adding that his endorsement could be decisive in a close election.
(Additional reporting by Steve Gorman and Edith Honan; Writing by Steve Gorman; Editing by Peter Cooney)