A leading conservative evangelical on Tuesday said Democratic presidential candidate Barack Obama had distorted the Bible and espouses a "fruitcake" approach to the US Constitution.
The comments by broadcaster James Dobson are among the sharpest religious attacks to date on the Illinois senator, who will face Republican John McCain in the November election.
Dobson, who has previously said he will not vote for McCain because of his past support for stem cell research, on Tuesday said the Arizona senator was not doing enough to stop gay marriage in his home state.
"This is a year when we have a lot of frustration with both political parties," Dobson said on his radio show, which reaches millions of conservative listeners.
The criticism by Dobson, head of the Focus on the Family organisation and a strong backer of President George W Bush in 2004, comes as Democrats are hoping to make inroads among evangelical voters who have been a pillar of Republican support.
Speaking on his campaign plane during a tour of western states, Obama said Dobson's comments, which focused on a speech the Illinois senator gave in 2006, were a misreading of his words and amounted to "making stuff up".
In the speech, Obama said religious people do not have a monopoly on morality and should couch their arguments in universal, rather than religious terms.
"That is a fruitcake interpretation of the Constitution," Dobson said. "What he's trying to say here is, unless everybody agrees, we have no right to fight for what we believe."
Obama said in the speech that certain passages of the Bible, if interpreted literally, could allow parents to stone their children and require that the Defense Department be abolished.
