A gay-rights group urged President Obama on Monday to speak in support of same-sex marriage in Maine and three other states that have ballot initiatives on it next month.

A Los Angeles-based organization called LegalizeLove.com said it plans to air a one-minute TV ad in those states using Obama’s own words when he declared support for gay marriage.

Two of the group’s organizers planned to deliver a bullhorn and a wedding cake with two grooms to Obama’s campaign headquarters in Portland on Monday, as the first stop in a campaign that will visit all four states that have marriage votes on the ballot Nov. 6.

Maine, Maryland and Washington will hold up-or-down referendums on legalizing same-sex marriage. Minnesota’s ballot measure proposes a constitutional ban on gay marriage.

All four states are expected to go for Obama in the presidential election, and the TV ads will help to ensure that the president’s support for gay marriage is “heard loud and clear,” said Eduardo Cisneros, who is traveling with his partner, Luke Montgomery, from state to state in a Volkswagen Beetle plastered with more than 1,000 “Legalize Love” bumper stickers.

“Because of a tight national race, we understand the president might not be able to hammer home his support for gay marriage himself, so we are stepping in to make sure this new TV spot using his own words gets that message out,” Cisneros said.

In May, Obama announced his full support for the right of same-sex couples to wed, creating a rallying point for gay-marriage supporters.

Mainers United for Marriage, the organization leading the gay-marriage campaign in Maine, took Obama’s announcement as blanket support for gay-marriage initiatives, said spokesman David Farmer. The president’s words have already had a positive effect on the campaign, he said.

“We feel like we have his support,” Farmer said. “He was pretty straightforward.”

Cisneros and Montgomery have produced a TV ad that features gay and lesbian couples in wedding dresses and tuxedoes with Obama’s speech quotes edited together.