Evangelical Christians have been asked to pray for "rain of biblical proportions" to fall on Senator Barack Obama as he accepts the Democratic nomination.

Stuart Shepard of Focus on the Family, one of America's leading evangelical groups, was shown in a video filmed at Denver's Invesco Field, where 75,000 are expected to cheer Mr Obama on Aug 28, asking Christians to pray for "torrential" rain.

"I'm talking 'umbrella-ain't-going-to-help-you rain," the former pastor and television meteorologist said. He explained on the video: "I'm still pro life, and I'm still in favour of marriage as being between one man and one woman. And I would like the next president who will select justices for the next Supreme Court to agree."

Mr Shepard, director of digital media at Focus Action, …