Conservatives seize on a must-pass spending bill to gain relief from environmental regulations they blame for constraining oil and gas development, while green activists lambaste the effort as a thinly veiled rollback of public health protections.

It nearly happened several times after Republicans rose in the 2010 congressional elections -- and this spring, it is happening in the Canadian Parliament. At the heart of the controversy is the alternately celebrated and maligned Keystone XL pipeline.

Canadian Prime Minister Stephen Harper and his Conservatives have made speedier development of the nation's emissions-heavy oil sands a top priority, using their latest budget bill that would ease several environmental laws and constrain greens' ability to organize against pipelines that would ship heavy crude out of the country. Hundreds of Canadian advocacy groups are pushing back today with an online protest, joined by top American conservationists and the Great White North's two main opposition parties.

"The attacks we're seeing on groups that speak out to defend the environment is being very clearly driven by powerful oil interests, and we saw these attacks intensify after the Keystone XL decision from President Obama," Environmental Defence Canada deputy campaign director Gillian McEachern said in an interview.

Dubbed "Black Out Speak Out," the campaign launched by McEachern's and other Canadian green groups says that "our land, water and climate are all threatened by the latest federal budget." Among the U.S. nonprofits darkening their websites in solidarity are the Natural Resources Defense Council (NRDC), 350.org and the Sierra Club.

The budget's "responsible resource development" section aims to trim the often-lengthy environmental review process for oil sands development by limiting the number of projects receiving a full study and reining in public participation in hearings on proposed pipelines. Harper's party also would curb protections for fish habitat not tied to commercial fisheries and add new constraints to political activity by Canadian green groups, which conservatives say are being unduly influenced by U.S. funding.

Canadian environmentalists "use funding from foreign special interest groups to undermine Canada's national economic interest," Joe Oliver, Harper's natural resources minister, wrote in an open letter published days before Obama rejected a permit for Keystone XL. "They attract jet-setting celebrities with some of the largest personal carbon footprints in the world to lecture Canadians not to develop our natural resources."

Movie stars Daryl Hannah and Margot Kidder were among those who joined 350.org founder Bill McKibben in White House demonstrations last year that were credited by pipeline friends and foes alike with moving the White House toward a veto of the 1,700-mile oil-sands crude pipeline (E&ENews PM, Aug. 23, 2011).

Keystone XL would not see any hurdles come down as a result of Canada's budget, having already received a green light from its National Energy Board. But the Northern Gateway pipeline that would stretch west from Alberta's oil sands through the more liberal province of British Columbia, opening lucrative Asian markets to Canadian fuel interests, could face a smoother path to construction if Harper's party wins the day.

McEachern said government representatives have made "contradictory statements" on how the budget would affect already-started project reviews such as those for the west coast pipeline. "Our fear is, it could mean they prematurely shut down public hearings on Northern Gateway and speed up the approval process," she added.

Oliver and other members of Harper's Cabinet, who would gain new power over environmental reviews under the proposed budget, are touring Canada today to drum up support for the plan and counter the green pushback. Conservatives defend the budget as a necessary spur for economically beneficial oil and gas development that, when slowed by burdensome regulatory processes, hurts the Canadian public at large.

Oil-sands extraction drives more than 100,000 jobs throughout Canada, a number expected to quintuple as more fuel is developed over the next two to three decades, according to the Canadian Association of Petroleum Producers.

The Conservatives' parliamentary majority is a significant obstacle to Canadian Liberals and New Democrats, both of whom joined the green protests today, in their efforts to slow or reverse the budget's path to passage. Its natural resources provisions are receiving extra review in a finance subcommittee of the parliament despite critics' preference for more debate in the environment committee, Canada's CBC News reported today.

Even if the budget becomes law, however, environmentalists on both sides of the border argue that Canadian Conservatives' bid to shake open the oil sands will come back to haunt them.

Criticism of U.S. environmental funding by Harper's ministers "is especially ironic when you consider that the oil industry is mostly multinational companies," NRDC international program director Susan Casey-Lefkowitz said in an interview. "This whole attempt to weaken the environmental movement has backfired. What I see is strength and growing unity between Canadian and U.S. groups to essentially stand up to the oil industry."