The House’s two biggest gay rights champions will be gone from the chamber after next year, leaving a void that advocates say will be tough to fill.

While Democratic Rep. Tammy Baldwin’s Senate bid in Wisconsin presents gay rights activists a historic opportunity to have representation in the Senate, Rep. Barney Frank’s (D-Mass.) retirement leaves the community without its most outspoken and grizzled veteran.

Rather than fill the shoes of the two giants who co-founded the LGBT Equality Caucus, Hill observers predict a broad coalition of Members — gay and straight — will collectively take up the mantle in the interim.

“The Equality Caucus is really vibrant, and there are many Members who are committed to the issues, and they will continue working on that,” said Cathy Hurwit, chief of staff to Rep. Jan Schakowsky (D-Ill.) who is a member of the caucus. “They are just hardworking, smart members, and I think they will step forward.”

Reps. Jared Polis (D-Colo.) and David Cicilline (D-R.I.) are the only other openly gay Members serving in the House. Polis took three weeks of paternity leave last month after he and his partner, Marlon Reis, announced the birth of their son, Caspian Julius. The Colorado Democrat has a coveted seat on the Rules Committee and is a frequent spokesman on gay rights issues along with Frank and Baldwin. Aides and observers say he is a natural fit to take the helm as the leading advocate for gay rights issues in the House, but spokesman Chris Fitzgerald demurred when asked about his boss’s future.

Still, that has not stopped supporters from floating Polis’ name.

“I think [he] would be the logical choice for who is going to take the helm,” said Rick Palacio, chairman of the Colorado Democratic Party.

Palacio said Polis fits the new mold of an LGBT lawmaker: someone who works with a wide spectrum of Members and who champions a broad portfolio of issues, not just those paramount to the gay community.

“There’s going to be a lapse because Barney had such deep relationships with everyone across the political spectrum. I see a little bit of that in Jared,” Palacio said. “Jared is very progressive but very pragmatic and pro-business. He has great relationships and works well across the aisle. They sort of operate in the same fashion.”

Cicilline, a freshman, is part of the coalition pushing for a repeal of the Defense of Marriage Act that defines marriage as between one man and one woman, and he is a co-sponsor of legislation to repeal the law. But while he has won plaudits from leaders for aggressively tackling his first term, he’s having a tougher time with his district. Providence, the city where he once served as mayor, is in dire fiscal straits, and Cicilline’s 2010 Democratic primary opponent Anthony Gemma has hinted he might run again.

The changing makeup of the LGBT caucus in the House comes at a time when the Human Rights Campaign, the powerhouse pro-gay-rights group, is going through its own changes. The group’s president, Joe Solmonese, is stepping down next year. Despite various successes during his tenure, including the repeal of the military’s “don’t ask, don’t tell” policy, the group has been criticized for not taking an aggressive enough approach, particularly with Congressional Democrats. 

Fred Sainz, vice president of communications for the HRC, acknowledged the gay rights community is now thrust into a transitional period because of Frank’s retirement and Solmonese’s departure. But, Sainz said, “New blood is good.”

“One of Barney’s greatest legacies is the new generation of leaders — gay and straight — that he’s inspired to make LGBT people and issues important to them a priority,” he said. “And while it will be a new era, we’re certain that our movement will keep moving forward as even greater majorities of Americans support our priorities.”

Sainz noted the Equality Caucus has grown to 99 members since its founding in 2008 and boasts three Republicans in its ranks, including Rep. Ileana Ros-Lehtinen (Fla.), one of the group’s vice chairmen. The membership, Sainz said, proves that “we’ve gotten to a point where it’s important for LGBT members to champion their issues, but these issues are no longer an issue that are advocated only by LGBT members.” 

Gay rights activists are also looking to Baldwin to be their biggest Capitol Hill spokeswoman after next year, noting that she will remain the go-to voice on LGBT issues if she wins her Senate race. But Republicans are eyeing a pickup opportunity in Wisconsin and are targeting the seat. If she loses, and Cicilline loses in a primary, Polis could potentially be the only openly gay incumbent to return to Congress. Six Democratic House candidates and one Republican candidate running in 2012 are openly gay, so the LGBT community is hopeful it will increase its numbers next year.

The dearth of veteran openly gay lawmakers means activists might need to work with their broader network of non-gay supporters. Members such as Schakowsky and Rep. Jerrold Nadler (N.Y.), a liberal leading the fight against DOMA, could see their portfolios broaden. While Frank noted at a press conference on Tuesday that skilled legislators are helpful to the cause, maintaining a human face on LGBT issues under the Dome is just as important.

“There’s no question that legislating is the most personal form of governance. … Personal factors mean a lot,” Frank said. “I think if you believe that we should be finishing the fight against legal discrimination based on sexual orientation and gender, it is important to have people who are gay and transgender and lesbian in the mix.”