President Barack Obama's decision to allow expanded offshore oil drilling prompted the first public criticism of his administration from Al Gore's environmental advocacy group, the Alliance for Climate Protection.

In this Jan. 28, 2009 file photo, former Vice President Al Gore testifies on Capitol Hill in Washington. Gore's statement is significant because it marks his first break with Obama on his signature policy issue, nearly two years after his enthusiastic endorsement gave the Illinois senator a jolt of momentum following the divisive Democratic presidential primary. (AP Photo/Susan Walsh, File) The organization, which the former vice president founded and chairs, put out a statement last week opposing the new policy.

The statement is significant because it marks Gore's first break with Obama on his signature policy issue, nearly two years after Gore's enthusiastic endorsement gave the Illinois senator a jolt of momentum following the divisive Democratic presidential primary.

Gore and the Alliance have appeared to avoid direct criticism of the president in the past when they've had disagreements, and have often cheered on the administration.

When Obama announced a plan to back construction of new nuclear power plants, another move denounced by environmental groups, Gore's group remained silent.

On the oil drilling announcement, however, the Alliance made its opposition clear.

"This plan continues our reliance on dirty fossil fuels - we cannot simply drill our way to energy security," the Alliance's CEO, Maggie Fox, said in the statement. "What we need now is presidential leadership that drives comprehensive clean energy and climate legislation that caps harmful carbon pollution, puts America back to work, ends our reliance on foreign oil and keeps us safe."

Asked if the Alliance statement represented the former vice president's views, Gore spokeswoman Kalee Kreider replied: "Former Vice President Gore did not release a statement, but the philanthropy he chairs did."

But Gore made his own views explicit on Wednesday when he sent a Twitter message hailing a "great post" from Fox on a blog reiterating her earlier statement.

Obama's announcement last week was seen as an olive branch to the oil industry and to fence-sitting senators whose votes are needed to pass sweeping climate and energy legislation that includes a cap on carbon emissions.

While other environmental groups have not been shy about criticizing compromises that they view as overly generous to industry interests, Gore and the Alliance have played the role of cheerleaders for Obama's yearlong push for a comprehensive bill. Their public statements have promoted positive developments in the process and lauded Obama's use of the presidential bully pulpit.

Where Gore has voiced frustration with the slow pace of U.S. action on climate change, he has directed his ire at the Senate, where a House-passed energy bill has languished for more than nine months. The Nobel laureate was disappointed with the outcome of the Copenhagen global climate talks last year, but in a New York Times op-ed in February, he said the failure came "in spite of President Obama's efforts." Instead, he blamed Senate inaction, saying it had "guaranteed that the outcome would fall far short of even the minimum needed to build momentum toward a meaningful solution."

The oil drilling announcement has divided some environmental advocates. While there is widespread opposition to the move on policy grounds, some have said it's an acceptable compromise if it helps to win support for the broader climate and energy bill.

The head of Clean Air Watch, Frank O'Donnell, said the Alliance has "by and large tried to promote an upbeat and positive message" about the climate legislation. "It's not in their interest to slam Obama," he said.

But the drilling expansion may have been a bridge too far, O'Donnell said. The policy, he said, "has absolutely nothing to do with climate."

"It's vote-buying, pure and simple," he said.

Other advocates were more surprised by the Alliance statement.

"They could have been looking for a way to demonstrate their independence," said Green Strategies President Roger Ballentine, who headed the White House Climate Change Task Force during the Clinton administration. He cautioned that he was speculating and did not know the reason for the Alliance's criticism.

Ballentine said he thought Gore would continue to play "an enormously constructive role" in the congressional debate. "I fully expect the former vice president to be supportive of a reasonable compromise," he said.