A White House environmental policy adviser who specialized in "green jobs" resigned on Sunday after an uproar over his previous affiliation with a September 11 conspiracy group.
Van Jones, special adviser on green jobs at the White House Council on Environmental Quality, apologized on Thursday after videotape surfaced of him using a crude epithet to describe Republicans and amid revelations he had signed a petition suggesting US government involvement in the 2001 attacks in New York and Washington.
The apology did little to quell Republican criticism, however, and President Barack Obama's chief spokesman gave only tepid support to the adviser on Friday.
Jones said he was resigning to avoid being a distraction in the administration's effort to pass healthcare reform and climate change legislation.
"On the eve of historic fights for health care and clean energy, opponents of reform have mounted a vicious smear campaign against me," Jones said in a resignation letter that was released to the media.
"I cannot in good conscience ask my colleagues to expend precious time and energy defending or explaining my past. We need all hands on deck, fighting for the future," he wrote.