Elated by a major court victory, US gay-rights activists are stepping up pressure on congress to repeal the military's 'don't ask, don't tell' policy this month. They want to avoid lengthy appeals and fear their chances for a legislative fix will fade after election day.

Congress voted in May to repeal the 17-year-old policy banning openly gay service members. Many majority Democrats in the senate want to take up the matter in the remaining four weeks before the pre-election recess, but face opposition from Republican leaders.

National gay-rights groups, fearing possible Democratic losses in November, urged their supporters to flood senators' offices with phone calls and emails asking that the senate vote on the measure during the week of 20 September.

"If we don't speak up now, our window for repeal could close," said Joe Solmonese, president of the Human Rights Campaign.

Supporters of repeal hope senators heed the ruling issued in Los Angeles by judge Virginia Phillips, who said 'don't ask, don't tell' was an unconstitutional violation of the due process and free speech rights of gays and lesbians.

The Log Cabin Republicans, a Republican gay-rights organisation, sued the government in 2004 to stop the policy, and Phillips said she would draft an order within a week doing just that.

The justice department has not yet said whether it will appeal against the ruling; a spokesman said lawyers were reviewing it.

Defence secretary Robert Gates and joint chiefs of staff chairman Mike Mullen – both in favour of repealing 'don't ask, don't tell' – said they prefer that the change wait until the military completes a review of the issue.