( The Associated Press)

The contribution is among the largest that has been made to Marylanders for Marriage Equality, which last week reported having raised $3.3 million for Question 6, the same-sex marriage measure that will appear on next month’s ballot.

In its announcement, the group played up the partisan affiliation of Singer, who has been a major donor to the campaign of GOP presidential nominee Mitt Romney and reportedly gave $1 million to help underwrite the cost of the Republican National Convention in Tampa. Singer, who has a gay son, has also given millions in recent years to further the cause of same-sex marriage.

“His investment in the equality and dignity of Marylanders reflects the growing bipartisan support to get Question 6 over the finish line in these critical final weeks,” said Chad Griffin, president of the Human Rights Campaign, a national gay-rights group heavily involved in the Maryland effort.

Singer’s donation comes as both sides of the same-sex marriage debate are trying to marshal resources for television ads in the three weeks that remain before the election.

Marylanders for Marriage Equality was set to debut a new ad Monday in the Washington media market featuring Julian Bond, chairman emeritus of the NAACP, who argues that “Maryland’s gay and lesbian families ... should share in the right to marry.”

The Maryland Marriage Alliance, the lead group opposing Question 6, last week reported having raised $838,621 for its campaign. In its television ads, the group has argued that children are better off with both a mother and a father.