Washington, Mar 26 (IANS): As the US Supreme Court hears two landmark cases on same-sex marriage, public support for such unions has witnessed a huge spurt with the coming out of several politicians on both sides of the political divide.

Two Democratic senators Monday joined other high-profile politicians like former Secretary of State Hillary Clinton in coming out in support of same-sex marriage ahead of the Supreme Court arguments Tuesday and Wednesday.

Its decisions are expected in June. The cases challenge California's "Proposition 8" and the federal government's Defence of Marriage Act, both of which define marriage as a union between a man and a woman.

"I support marriage equality because it is the fair and right thing to do," wrote Senator Mark Warner, a former governor of Virginia, on his Facebook page.

Fellow Democratic Senator Claire McCaskill of Missouri similarly endorsed same-sex marriage, saying she had "come to the conclusion that our government should not limit the right to marry based on who you love."

Both Virginia and Missouri have large swaths of conservative voters, who are opposed to unions between gays and lesbians.

Earlier this month, Senator Rob Portman became the first Republican in the Senate to back same-sex marriage, explaining his decision was influenced by his son, who is gay.

Meanwhile, a new national poll indicates that the percentage of Americans who say they have a family member or close friend who is gay or lesbian is on the rise. And that increase matches a jump in the percent of the public who support legal same-sex marriages.

According to a CNN/ORC International survey, 57 percent say they have a family member or close friend who is gay or lesbian, up 12 points from 2007.

The number of Americans who support same-sex marriage has risen by almost the same amount in that time - from 40 percent in 2007 to 53 percent today.

"The changes have been so swift that it is sometimes surprising to remember how many gay men and lesbians were until recently in the closet and how many hurdles there have been along the way," wrote John Harwood in The New York Times.

"We were all hiding," he quoted former Representative Barney Frank, Democrat of Massachusetts, who in 1987 became the first member of Congress to voluntarily disclose his homosexuality, as saying.

"At the time, the public disapproval of homosexuality - so powerful that gay men and lesbians hesitated to identify themselves, much less seek political change - helped stunt the movement's emergence," Harwood wrote.