Vermont Senator Patrick Leahy is the fifth senator to publicly flip on the issue of gay marriage this year.

Leahy, a Democrat, is the current chairman of the powerful Senate Judiciary Committee and the fourth most senior U.S. senator.

In an interview with Vermont Public Radio Monday, Leahy reversed his position on the Defense of Marriage Act (DOMA), the 1996 federal gay marriage ban.

“Well, I think now that you have states that are voting for and having same-sex marriages – Vermont has, Massachusetts has, New Hampshire, others, Connecticut – the Defense of Marriage Act is unnecessary, should be repealed,” Leahy said.

Gay rights groups have always counted on Leahy as a strong ally, but like many other Democrats he did vote for DOMA.

“If I was voting – if this matter was coming the first time, I'd vote differently than I did then,” Leahy added. “Because I think the states are now ahead of the Congress on this. I was concerned at the time I voted for it that we may be facing the possibility of having a national law that would override states and would not give Vermont to do what it want or California the freedom to do just the opposite of Vermont.”

Leahy is the fifth U.S. senator to publicly endorse gay marriage this year.

Last month, Connecticut Senator Christopher Dodd, a Democrat, endorsed gay marriage in a Senate blog post. “I am also proud to now count myself among the many elected officials, advocates, and ordinary citizens who support full marriage equality for same-sex couples,” Dodd said.

In January, Kirsten E. Gillibrand, the upstate New York congresswoman chosen by Governor David Paterson to fill the Senate seat vacated by Secretary of State Hillary Clinton, said “I will advocate for marriage equality” in her acceptance speech to the post.

New York Senator Charles Schumer told the New York Daily News in March that “equality is something that has always been a hallmark of American,” when asked to verify a press release by Empire State Pride Agenda, a group that lobbies for gay marriage in New York, that claimed the senator had reversed course on gay marriage.

And two months later, after the Iowa Supreme Court legalized gay marriage, Iowa Senator Tom Harkin also made an about-face. Speaking on the PBS program Iowa Press, Harkin said he would vote against a ban on gay marriage in Iowa.

“You know there's always going to be some who feel that they have to push this issue [gay marriage], and, for whatever reason, they are going to push it and try to divide people, but they're on the losing end. They are on the losing end of history,” Harkin said.

All five senators hail from states where gay marriage is legal or, where, as in the case of New York, there is widespread support for granting gay and lesbian couples the right to marry.