A coalition of gay groups and trade unions have appealed to former US President Bill Clinton to reconsider a speaking engagement at a San Diego hotel this Sunday.
The Manchest Hyatt Hotel is owned by Doug Manchester.
He donated $125,000 (£86,890) to the campaign to pass Proposition 8. It was approved by Calfornia voters in November and denied gay and lesbian couples the right to marry, which had been legal since June.
The hotel is in an ongoing dispute with trade unions about working conditions for housekeepers and has been the subject of a boycott since April 2008.
San Diego Pride and Equality California are among groups calling on President Clinton to cancel his speech to the International Franchise Association.
“We respectfully ask that you to move your speech to another location so you do not have to violate this boycott,” the coalition said in a letter to the former Preisdent.
“Neither labour nor the gay community can tolerate a hotel whose profits are used to take away equal rights for gay couples and create poor working conditions for women and immigrants.”
A spokesman for Bill Clinton said that he would refuse to speak if he had been invited by Mr Manchester or the hotel.
“He’s obviously sympathetic to this cause,” Clinton spokesman Matthew McKenna said.
“I don’t think you can name a leader in the world who has done more to advance gay and lesbian issues.”
However, he will attend the event and is likely to face a picket from gay activists and union members.