A radio station host and former Advocate editor-at-large has alleged that Mark Buse, presidential candidate John McCain’s chief of staff, is gay.

On Monday, Michelangelo Signorile claimed on his blog that he has been contacted by three sources outing Mr Buse, Advocate.com reports.

Mr Buse, 44, was a lobbyist for corporations AT&T and ExxonMobil prior to taking his position in the McCain campaign.

Mr Signorile, who hosts a self-titled show on Sirius Satellite Radio’s OutQ channel, wrote in his blog that he was contacted by Brian Davis, who claims to have had an intimate and long-term relationship with Mr Buse.

Mr Davis told the radio host that he met Buse in 1986 in a bar called Connections in Phoenix, when Mr Buse worked as an intern for McCain, then a member of the House of Representatives.

Allegedly, Mr Buse and Mr Davis lived together in Washington DC for a year, before Mr Buse left him for his current partner. Senator McCain has been described by some as anti-gay.

In July, he stated that he “does not believe” in gay adoption, a comment that was later retracted by his campaigns Director of Communications, Jill Hazelbaker.

In August, when discussing gay marriage, Senator McCain said: “Union; a union between man and a woman, between one man and one woman. That’s my definition of marriage.”