The Human Rights Campaign announced its endorsement Thursday of Kirsten Gillibrand, the appointed U.S. senator from New York who will stand for election in 2010.

Gillibrand, a former congresswoman from upstate New York, was appointed by Gov. David Paterson in January to serve the remainder of the term begun by Hillary Clinton, who left the Senate to become secretary of State.

HRC cited Gillibrand’s vocal support since taking office for a repeal of the military’s “don’t ask, don’t tell” policy, and her stature as “the first U.S. senator from New York to support full marriage equality for same-sex couples.” Sen. Chuck Schumer, also from New York, announced his support for marriage equality this fall.

“Senator Gillibrand has emerged as one of the strongest advocates in the Senate for full equality for the LGBT community,” said Human Rights Campaign president Joe Solmonese in a statement released by the group. “From her personal lobbying of the New York legislature in support of marriage rights to helping garner support for a Senate hearing on repealing ‘don’t ask, don’t tell,’ Gillibrand has time and again stood for fairness for all.”

While initially thought to be vulnerable among downstate New York voters in a Democratic primary because of her more conservative upstate positions on issues like gun control, Gillibrand has evolved to fend off significant challenges within her own party. In a general election, however, she could face a Republican with statewide name recognition, such as former governor George Pataki or New York City mayor Rudy Giuliani, depending on whether they decide to run.