It was meant to be a unifying show of strength at a critical juncture in the gay rights movement.

But a march planned for Sunday on the Mall in Washington is exposing deep divisions among gay rights advocates around the country as they grapple with whether to continue pushing for gains state by state, or embrace a more aggressive strategy to pressure the Obama administration and Congress for federal action.

The march is occurring as referendum campaigns in Maine and Washington State seek to overturn laws that expand the rights of same-sex couples. Faced with the specter of a defeat similar to the passage of Proposition 8 in California last year, gay rights advocates have split over whether an undertaking as large and expensive as a march on Washington will come at the expense of ballot fights this fall.

The debate around the march  the first mass gathering of gay rights supporters in Washington since 2000  suggests that as the AIDS crisis has receded, gay activists have had a more difficult time mobilizing around a more diffuse agenda, including issues like same-sex marriage and anti-discrimination laws.

“We can be thankful that the threat of AIDS has ebbed and is no longer the death warrant it was, but that also turns down the flame of consciousness,” said Dudley Clendinen, a scholar of the American gay movement who teaches at Johns Hopkins University.