With his future at stake, Lt. Dan Choi hopped a train from New York to catch Tuesday’s Senate Armed Services Committee hearing on repealing the military’s “don’t ask, don’t tell” policy on gays serving in the armed forces.

“I thought that if they were going to talk about whether I should be fired or not, I should show up,” said Choi, a West Point graduate and Arabic linguist who is facing discharge from the New York Army National Guard after revealing last year on national television that he is gay.

He was among the policy’s opponents and proponents who packed the hearing, which marked the start of what is expected to be an intense year of lobbying on the emotional issue.

At the hearing, Defense Secretary Robert Gates announced he was commencing a yearlong study on how to end the policy as well as ushering in less onerous enforcement of it. Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, told Senators he supported letting gays serve openly. “It would be the right thing to do,” he said.

Both men, however, acknowledged that it will be up to Congress to undo the policy — a challenging task considering it is an election year and the polarization that has led to gridlock in other areas such as health care reform.

As a result, both sides are marshaling their forces for the legislative battle ahead. To make his case against repealing the policy, Sen. John McCain (R-Ariz.), the ranking member on the committee, cited a letter from 1,100 retired military officers supporting the 1993 law that bars gays from serving openly.

Conservative religious groups are also weighing in. Five Orthodox Jewish men left Monsey, N.Y., at 3:30 a.m. to make the noon hearing to express their objections to changing the policy.

“We believe this is a pernicious assault on religious liberties,” said Rabbi Noson Leiter of Torah Jews for Decency.

Meanwhile, in the back of the room in the Dirksen Senate Office Building, a representative from the Traditional Values Coalition handed out a release that said, “We don’t need someone sitting in a foxhole concerned about whether or not the night will turn into ‘date night’ for someone sitting beside him.”

But representatives from gay rights and military groups huddled with reporters after the hearing to assert that the nation is ready to embrace change.

Jon Soltz, co-founder of VoteVets.org, said a younger generation of soldiers is comfortable with serving alongside gays. He also predicted the debate would be far less divisive than the 1993 deliberations in part because Mullen, the top military official, supports gays’ right to serve openly. In 1993, the top military brass opposed gays serving openly.

Even with the change in attitudes, gay rights groups are preparing national campaigns and lobbying strategies on Capitol Hill to ensure the policy is changed.

“I think this will be a make or break year for ‘don’t ask, don’t tell,'” said Alex Nicholson, executive director of Servicemembers United, a group that supports gays in the military.

The biggest challenge will be in the Senate, where legislation is more easily blocked by the minority party.

Even garnering enough support in the Senate Armed Services Committee will be tough, Nicholson said. His group is now targeting four moderate Democrats on that panel who have not committed to the repeal: Sens. Bill Nelson (Fla.), Ben Nelson (Neb.), Jim Webb (Va.) and Evan Bayh (Ind.). Nicholson said he expects the only Republican on the panel likely to vote for the repeal is Sen. Susan Collins (Maine).

On the House side, the sponsor of the legislation to allow gays to serve openly, Rep. Patrick Murphy (D-Pa.), has already lined up 187 co-sponsors, which is still short of the 218 votes needed to pass the measure. But Nicholson voiced confidence that enough Members will support overturning the policy. However, the measure still must go through the House Armed Services Committee, which is chaired by Rep. Ike Skelton (D-Mo.), who does not favor repeal.

The Human Rights Campaign, a heavyweight among gay rights groups that spent $1.3 million on lobbying last year, is also expected to throw its considerable resources at trying to repeal the ban.

President Joe Solmonese said that while he would “like to see the process move faster,” he was pleased by the statements of Gates and Mullen.

Solmonese said his group has launched a campaign to bolster lawmakers who support repeal of the policy. To help make its case, the HRC has enlisted the politically connected lobbying firm Elmendorf Strategies. The HRC also has a contract with lobbying firm the Raben Group.

The gay rights groups have also recently gained a powerful ally. The American Medical Association, at its annual meeting in Texas late last year, approved a resolution opposing “don’t ask, don’t tell,” arguing that it violates doctor-patient confidentiality.

Paul Wertsch, a Wisconsin physician whose son is gay, drafted the resolution after he was informed that the military authorities could inspect medical records of soldiers and use mentions of sexual orientation as reasons for discharge.

“Anything that interferes with the physician-patient relationship is counterproductive to good health,” Wertsch said.

While gay rights groups have long been preparing for a legislative fight, a number of opponents of repeal, including veterans and conservative groups, are just beginning to rally.

Elaine Donnelly, president of the Center for Military Readiness, a Michigan group that opposes gays in the military, said many military and veterans groups have not been vocal because “the issue has been settled.”

But she predicted these groups would become more active “now that the president has put it up front on his agenda.”

Obama’s pledge in his State of the Union address to repeal the policy drew a strong response from the socially conservative Family Research Council.

President Tony Perkins issued a statement accusing Obama of putting forth a proposal to “sexualize the military,” saying, “the timing of the president’s call in the midst of two wars shows that he is willing to jeopardize our nation’s security to advance the agenda of the radical homosexual lobby.”

Some of the military and veterans groups have been more measured in their response.

The Veterans of Foreign Wars last year approved a resolution opposing a repeal of the “don’t ask, don’t tell” policy. But VFW spokesman Joe Davis said the group wanted to see how military officials responded to the proposed repeal.

“We’re in a wait-and-see mode,” Davis said.

A poll taken last spring by the Pew Research Center found that 59 percent of Americans supported allowing gays and lesbians to serve openly in the military. However, a Military Times poll in 2008 found that 58 percent of military personnel who were subscribers did not favor allowing gays to serve openly.

“There is no question there is resistance in the military. It has a long history of hostility to homosexuality,” said Nathaniel Frank, who has written about the history of gays in the military and is a senior researcher at the Palm Center at the University of California at Santa Barbara. But Frank also said the political environment has changed dramatically since 1993.

Choi, the lieutenant facing discharge, said he and other gay soldiers, whom he called his “battle buddies,” have been promoting the repeal. He dismissed the suggestion that the issue needs more study.

“We all roll our eyes,” he said. “What are you going to study?”