Paul Singer (Reuters photo)

The latest campaign finance reports for political action committees participating in the same-sex marriage referendum are due tonight at midnight, but one at least one pro-marriage equality PAC has filed early. 

The report features a big-time national donor: Paul Singer. 

Singer’s $150,000 donation to the Freedom to Marry PAC was noted in Monday’s story about Republican politicians who have decided to join the effort to legalize same-sex effort in Maine. However, the billionaire hedge fund manager’s involvement in the Maine effort is noteworthy for a few reasons.

Singer is perhaps best known for his support of Republican candidates. A recent New York Times story noted that Singer, who runs the firm Elliott Management in New York City, raised $5 million dollars for presidential hopeful Mitt Romney during a single fundraiser. 

But Singer, whose son and son-in-law are gay, is also known for supporting same-sex marriage efforts in other states and he has spent close to $10 million to advance the cause. Singer has given $1 million to the American Unity PAC, a new super PAC designed to encourage Republican candidates to support same-sex marriage. Campaign finance laws also shields the identities of donors to the PAC.

Singer’s deep pockets have already provided protection for Republicans who have supported same-sex marriage. Today is the one-year anniversary of the same-sex marriage law enacted by the New York State Assembly.

Passage of the law required Republican support. The National Organization for Marriage, which opposes same-sex marriage, immediately vowed to spend $2 million to remove the GOP lawmakers from office. However, Singer pledge to donate at least $250,000 to each of the legislators to counter the threat. 

Fred Sainz, the vice president of communications for the D.C.-based Human Rights Campaign, said Singer has been "a tremendous" advocate for same-sex marriage, adding that his financial pledge to help the New York GOP assembly members irked would-be Democratic opponents. After all, the Democratic party has traditionally been more sympathetic to same-sex marriage. 

Singer, in a rare press interview, told NYT columnist Frank Bruni, said that the GOP should reconsider its position on same-sex marriage. 

"The Republican Party can be more of a big tent and this issue is a part of that," he told Bruni. 

Singer isn’t saying much about his involvement in the Maine same-sex marriage referendum. A spokesman for Singer declined to comment. 

However, donations to the Freedom to Marry PAC show that corporations are seeing the benefit of backing same-sex marriage. Freedom to Marry has raised $296,805 so far. Several other contributors stand out, including executives for Cargill, Verizon and The Council of Insurance Agents and Brokers. 

The other PACs involved in the same-sex marriage referendum are expected to file their 42-day post-primary report close to the midnight deadline.