A prominent equal rights organization that spearheaded Maine’s same-sex marriage law announced Friday that it is endorsing Democrat Sara Gideon in her attempt to unseat incumbent Republican U.S. Sen. Susan Collins in November.

EqualityMaine, which advocates for equal rights for members of Maine’s LGBTQ community and their families, announced its support for Gideon in a news release, stating it was the first time since 2002 that the group has taken a position against Collins, who is seeking her fifth term.

“Susan Collins has been in the Senate for 24 years – ample time to demonstrate that she will fight for us. But again and again, Susan Collins has been a disappointment,” Darlene Huntress, a member of the EqualityMaine board, said in a prepared statement.

In a statewide referendum vote in 2012, Maine approved one the nation’s first laws legalizing same-sex marriage, an effort spearheaded by EqualityMaine.

The organization has never endorsed Collins, but has largely remained neutral in her more recent re-election campaigns.

The organization, which includes more than 70,000 Mainers, last endorsed an opponent of Collins in 2002, when they threw their support to Democrat Chellie Pingree, who now serves in the U.S. House representing Maine’s 1st Congressional District.

Collins, who has previously enjoyed the support of many LGBTQ voters in part for her efforts to repeal the “don’t ask, don’t tell” policies in the U.S. military, is now locked in what many believe is the toughest re-election campaign of her political career.

In July, the Human Rights Campaign, a national organization that advocates for LGBTQ rights, also endorsed Gideon. The group had previously endorsed Collins.

Collins has consistently trailed Gideon, the outgoing speaker of the Maine House Representatives from Freeport, in public opinion polls, including in a new Colby College poll released on Friday.

The four-way U.S. Senate race also includes independent candidates Max Linn, a conservative activist who previously attempted a U.S. Senate bid in Maine as a Republican, and Lisa Savage, a longtime Green Party activist and organizer.