America is again on the brink in one of its most divisive culture war flash points. But the first political test of Don’t Ask, Don’t Tell in 17 years now appears unlikely to bring about a truce.

The policy that declares homosexuality incompatible with service life has survived two wars, troop stop-loss measures, a 78% disapproval rating and near universal condemnation by the nation’s legal minds. Few politicians, Democrat or Republican, now claim it was ever a good idea. But tomorrow it is expected to survive again after key senators could not be persuaded into joining a divisive vote on the eve of an election.

The upcoming vote in the Armed Services Committee was a compromise reached between the White House  — rapidly losing support from its donor base on the Left — and gay and lesbian lobby groups, which organise much of that campaign fundraising. Crikey has been told the Pentagon was not included in those meetings.

A Pentagon spokesman announced earlier today Defence Secretary Robert Gates will support an amendment to the routine Defence Authorisation Bill repealing the ban, although he is not pleased politicians are pressing ahead before he could finish a 12-month survey of troop opinions on the matter.

The White House budget director, Peter Orszag, made the news of the compromise public yesterday in a letter to lawmakers, signalling President Obama was prepared to spend political capital on the issue despite a lukewarm reception from several of the military’s service chiefs.

The Pentagon, rather than politicians, has been the most unreadable in the months leading up to this vote, switching its position, or back-flipping in the American lexicon, on a weekly basis. A parade of service chiefs and secretaries have told Congress they will continue to enforce the law, then they won’t, then they will, but reluctantly, then they will because they believe in American freedom.

Chairman of the Joint Chiefs, Admiral Mullen’s ground-breaking statement in support of gay and lesbian troops quickly became lost in muddle of messages. Mullen and Gates signed a letter earlier this month strongly discouraging congress from taking any steps at this time.

Senator John McCain, facing re-election challenges from the Right, has been the most vocal politician to support keeping the law until there is unanimous support among the chiefs. However, Service Members Legal Defence Network, a group of veterans and lawyers opposing the ban, told Crikey their focus has shifted in recent weeks from the military community to politicians.

Aubrey Sarvis, an army veteran and the group’s executive director, called the compromise a “dramatic breakthrough” that came following a hammering campaign involving bloggers, activists, lawyers and veterans.

“President Obama’s support and Secretary Gates’ buy-in should insure a winning vote, but we are not there yet,” he said. “The votes still need to be worked and counted.”

Crikey was there as some 350 veterans visited their representatives’ Capitol Hill offices this month calling for the ban’s repeal, after about 250 lawyers did the same last month. Of the more than 100 politicians from both parties that held meetings none defended the law — but many questioned whether now was the time to change it.

Human Rights Campaign spokesman Michael Cole told Crikey Mullen and Gates have been clear on one point: “The Pentagon Working Group study is about how to repeal, not whether to repeal.”

Opponents of repeal such as the Centre for Military Readiness, a think-tank that also opposes expansion of women’s role in the services, have been pressing the flesh and appearing on cable news channels with a regularity not seen since the law first passed in 1993. Estimates from the Palm Centre, a Californian think-tank, put the number of gay and lesbian troops in the tens of thousands of the two million Americans who serve in active duty and reserves.

One more active duty soldier with two tours of Iraq came out on prime time television today following announcement of the compromise vote. Anthony Bustos is following dozens who have come forward to the media in recent months, as well as six veterans who were arrested for chaining themselves to the White House fence during a protest this month.

Last week Australian Defence Force’s Lieutenant Colonel Mick King told a forum in Washington that repealing the gay ban had had no impact on the ADF. King, a young officer when Australia’s military gay ban was repealed in 1992, said there was “some gnashing of teeth by some individuals [but] for the most part the policy came and it went”.