President Obama is marking Gay Pride Month with a concerted push to mobilize lesbian, gay, bisexual and transgender  voters, who his re-election campaign believes are a key constituency in hotly contested swing states.

In a new five-minute, documentary-style campaign video, Obama appeals to his supporters by casting himself as the most progressive U.S. president on gay rights issues in American history.  He also reflects personally on how he was inspired to become an advocate through relationships with LGBT friends and family, U.S. military service members, and the mother of anti-gay hate crime victim Matthew Shepard.

"Meeting people like Judy Shepard, and not only hearing the heartbreaking tragedy of Matthew but also the strength and determination she brought to making sure that never happens to young people anywhere in the country again," is what he says moved him.

Obama also said  the stories of gay and lesbian service members who have fought and died for the country also "made me passionate."

"I don't think there was a single moment LGBT issues became important to me. It was an accumulation of a lifetime of friends, family and people I've met who have helped me understand how the fight for LGBT rights is consistent" with America, he said.

The film is  narrated by actress Jane Lynch, who stars in the hit show "Glee."

"That passion drove him to make more significant advances for LGBT Americans than any other president who came before him," Lynch says.

Earlier today, the Obama campaign also kicked off a grassroots organizing campaign specifically targeting gay voters. "LGBT Americans for Obama" will focus on enlisting volunteers and turning out votes in Pennsylvania, Colorado, Nevada and Michigan, the campaign said.

Obama campaign strategists believe the president's achievements in gay rights, coupled with his newfound support for same-sex marriage, is one of the strongest selling points of his first term.

They regularly rattle off the repeal of "don't ask, don't tell," signing the Hate Crime Prevention Act into law, ceasing a defense of the federal Defense of Marriage Act, and executive actions to prohibit discrimination based on gender identity in the federal government.