An outspoken and polarizing voice in conservative Christian politics has resigned from the National Association of Evangelicals after a radio interview in which he voiced support for same-sex civil unions and said he was "shifting" on gay marriage.

The Rev. Richard Cizik's comments - made on a Dec. 2 "Fresh Air" broadcast on National Public Radio - triggered an uproar that led to his stepping down Thursday as NAE vice president of governmental affairs.

A fixture in Washington for nearly three decades, Cizik (pronounced SIGH-zik) has played a key role in bringing evangelical Christian concerns to the political table. But in recent years, he earned enemies in the movement for pushing to broaden the evangelical agenda. His strongest focus was on "creation care," arguing that evangelicals have a biblical responsibility to the environment that includes combatting global warming.

The Rev. Leith Anderson, a Minneapolis-area pastor who serves as NAE president, said Thursday that the group was not backing away from its environmental stances. Cizik's resignation was necessary, he said, because some of his answers in the radio interview did not reflect NAE values and convictions.

"Any organizations that speak to controversial issues are going to have critics," Anderson said. "What was different this time was our individuals and organizations felt there was a loss of credibility for him clearly espousing our positions and values. When you lose that, it's very difficult to re-establish."

Cizik did not respond to requests for comment. The NAE, an umbrella group for thousands of churches, said in a statement that he had expressed regret, apologized and "affirmed our values. *