Several leading gay advocacy groups said Tuesday they are abandoning the Employment Non-Discrimination Act, commonly known as ENDA, following the Supreme Court’s Hobby Lobby decision last week.

The reason is a religious exemption added to the Senate version of the bill to win conservative backing. It would allow religious-affiliated institutions, including universities and hospitals, to discriminate against lesbian, gay, bisexual and transgender people in employment.

The bill passed the Senate last fall. Its prospects were already grim in the House, where Republicans refused to schedule a vote, and with Tuesday’s mass abandonment, the bill’s chances of passage are all but nonexistent.

A big exception to the exodus is the Human Rights Campaign, the nation’s largest gay lobbying group, which said it will continue to support the legislation.

Kate Kendell, executive director of the San Francisco-based National Center for Lesbian Rights, said her group has long been disturbed by a religious exemption in the proposed legislation. The exemption was part of a compromise engineered by Utah Republican Orrin Hatch to win conservative support.

Kendell said other civil rights laws contain “more modest exemptions that permit a religiously affiliated employer to prefer people of their own religion in key positions where that matters.” But the ENDA exemption, she said, “would permit is any religiously affiliated employer to refuse to hire or to terminate” an employee whose sexual orientation is deemed inconsistent with the employer’s religious views.

The exemption “particularly singles out LGBT people,” Kendell said. “Not only do we feel like this would essentially give carte blanche to employers to discriminate against LGBT employees, but after Hobby Lobby, there’s really no limit. It’s the classic case of this exemption eviscerating the protections ENDA was designed to provide.”

The Supreme Court ruled in Hobby Lobby that closely held businesses do not have to offer their employees contraceptive coverage if doing so conflicts with the owner’s religious beliefs. Although the ruling applied to women’s contraceptive rights, gay rights groups viewed the decision with alarm.

The National Center for Lesbian Rights went on record against supporting ENDA a few weeks ago. It was joined Tuesday by the American Civil Liberties Union, the Transgender Law Center, Lambda Legal,Gay & Lesbian Advocates & Defenders and the National Gay and Lesbian Task Force Action Fund.

Human Rights Campaign spokesman Fred Sainz told us in an e-mail that his group “supports ENDA because it will provide essential workplace protections to millions of LGBT people.”

ENDA was first introduced in 1994. When the Senate voted 64 -32 for passage in November, 10 Republicans joined 54 Democrats in support.