SEATTLE, Wash. -- A Christian pastor is urging a nationwide boycott of Starbucks for the company's support of same-sex marriage in Washington. 

In an online message published a day before Washington's Senate passed a bill legalizing gay marriage, Pastor Steven Andrew of USA Christian Ministries predicted that the Seattle-based coffee giant could lose 80%of its customers if Christians get their coffee elsewhere. 

Starbucks is one of more than 100 companies that pledged support for legalizing gay marriage in Washington. 

Washington's state House is expected to pass the legislation next week, and Governor Chris Gregoire promises to sign it. 

Opponents say they will put the measure before voters in a referendum this fall.