PORTLAND — Music celebrity Lady Gaga will be the featured speaker at a Monday rally in Deering Oaks to support repeal of the military’s “don’t ask, don’t tell” policy, which bars gays and lesbians from openly serving in the military.

The rally, which is scheduled to start about 4 p.m. at the park’s bandstand, was organized by the Service Members Legal Defense Network.

The national organization is holding the rally in an effort to bring pressure on Maine Sens. Olympia Snowe and Susan Collins in advance of Tuesday’s Senate vote on a military spending bill that includes the repeal of “don’t ask, don’t tell.” Sen. John McCain, R-Ariz., has threated to block passage of the bill if the repeal provision is left in.

Aubrey Sarvis, executive director of the Service Members Legal Defense Network, said Lady Gaga is a passionate supporter of repealing the policy and views Maine’s two Republican senators as holding critical votes to breaking a threatened Republican filibuster.