The National Organization for Marriage (NOM) raised less money in 2011 than it did in the previous year.

According to the Human Rights Campaign (HRC), the nation's largest gay rights advocate, NOM saw a steep decline in the amount of money it raised in 2011.

In 2010, the group, which fights against the adoption of gay-inclusive marriage laws, reported raising $9.1 million.

NOM reported raising $6.2 million in 2011, a 30 percent drop from the previous year.

The group had previously experienced significant financial growth each year since its 2007 founding to advocate for passage of Proposition 8, California's gay marriage ban.

Documents also reveal that 75 percent of NOM's contributions ($4.7 million) came from two anonymous donors.

On November 6, NOM, the nation's most vociferous opponent of marriage equality, suffered setbacks in five campaigns in which it had invested upwards of $5.7 million. In three states – Maine, Maryland, and Washington state – voters legalized the institution, while Minnesotans rejected an effort to ban it. In Iowa, NOM lost a campaign to oust state Supreme Court Justice David Wiggins, who was targeted by conservatives angry over the high court's unanimous 2009 ruling which brought gay marriage to the Midwest.

(Related: NOM's Brian Brown says money to blame for election night losses.)