WASHINGTON – President Barack Obama’s nominee to be the nation’s top energy regulator withdrew Tuesday, conceding he did not have enough support for confirmation.

Ron Binz, a former Colorado energy regulator and strong backer of renewable energy, was opposed by at least half of the 22-member Senate Energy Committee, including all 10 Republicans and at least one Democrat.

Opponents said they considered Binz’s views to be outside the mainstream and were troubled by his comment that natural gas may be a “dead-end” fuel. Republicans said they were concerned that Binz was not truthful when he assured them that he was not part of a coordinated effort by a green-energy group and a Washington lobbying firm to boost his nomination to head the Federal Energy Regulatory Commission.