Arlen Specter, the Democrat senator for Pennsylvania, has changed his mind on the issue of gay marriage.

In 1996, he voted for the Defence of Marriage Act (DOMA), which prohibits the federal government from recognising gay marriage. In 2006, he voted for a constitutional amendment to ban gay marriage in his state.

But writing in the Huffington Post this week, Specter said it was time to repeal DOMA and allow states to decide for themselves.

He wrote: “Enacted 13 years ago when the idea of same sex marriage was struggling for acceptance, the Act is a relic of a more tradition-bound time and culture.

“Connecticut, Iowa, and Massachusetts have already passed laws recognizing same sex marriage and other states are moving in that direction. The states are the proper forum to address this divisive social and moral issue, not the Federal Government with a law that attempts to set one national standard for marriage.”

Specter also called for the ban on openly gay personnel in the US military to be repealed and restated his support for the Employee Non-Discrimination Act 2009, of which he is a co-sponsor.

According to On Top magazine, he is the sixth senator to do a public U-turn on gay marriage this year.

New York senator Charles Schumer said in March that he now supported gay marriage. In January, New York senator Kirsten E Gillibrand said she would fight for marriage equality, while Connecticut senator Christopher Dodd said he supported full marriage equality for gays in June.

Patrick Leahy, the Vermont senator, and Iowa senator Tom Harkin have also changed their views this year.