Support for gay rights threatens to derail Solicitor General Elena Kagan's possible Supreme Court nomination.

Kagan, whose name is often mentioned as a contender to succeed retiring Justice Paul Stevens, faced a difficult confirmation last year in the Senate, where social conservatives attacked her for supporting gay rights.

Conservatives argue that Kagan mostly likely supports giving gay and lesbian couples the right to marry.

As proof they cite a 2005 Supreme Court challenge to an appellate ruling that permitted law schools to limit the military's presence at campus recruiting events. Kagan was one of 40 Harvard Law School professors who signed a friend-of-the-court brief in support of the ruling.

The brief argued that the military's “don't ask, don't tell” policy that bans gay troops from serving openly violates the legal profession's anti-discriminatory policies.

Kagan, 49, called the policy “a profound wrong – a moral injustice of the first order,” in a an email to faculty and students, the Wall Street Journal reported.

The Supreme Court unanimously disagreed with the lower court ruling.

At her Senate confirmation hearing, social conservatives attacked Kagan, saying she was too liberal.

“Ms. Kagan's extreme rhetoric makes it highly likely that she also favors same-sex marriage, both as a matter of policy and as a supposed federal constitutional right,” opponents – including anti-gay rights stalwarts the American Family Association and Focus on the Family – warned in a letter.

In a blog post, the anti-gay rights group Family Research Council helmed by influential social conservative Tony Perkins prayed against the confirmation of various Obama nominees, including Kagan: “Please pray over these nominees. May God move to prevent confirmation of those who will do harm [to] our nation! May He restrain those who Senate conservatives have little power to prevent from confirmation!”

“There is no federal constitutional right to same-sex marriage,” Kagan responded to an inquiry by Senator John Cornyn, a Texas Republican, in a written follow-up to her confirmation.

Just yesterday, Cornyn, a member of the Senate Judiciary Committee, said he would be OK with an openly gay court nominee.

“As long as it doesn't interfere with their job, it's not a particular issue,” he told The Hill.

Supreme Court justices are appointed for life.