As industry, environmentalists, labor and locals gear up for the start of public hearings on the much-debated Keystone XL oil pipeline, the green group behind recent White House sit-ins against the $7 billion project is turning to a positive message at global rallies tomorrow.

The day of demonstrations by 350.org, the group founded by climate activist and Keystone XL critic Bill McKibben, carries a broad aim of stoking grass-roots global warming activism. But McKibben's central role in drawing greens' battle lines against the pipeline -- to coax an Obama White House seen as rarely prioritizing their concerns into rejecting its Canadian oil-sands crude supply -- makes his "Moving Planet" events the latest show of force from XL opponents.

"We're trying very consciously to build a big movement around climate change -- sometimes that means doing things that are happy, and that's what this weekend is about," McKibben said in an interview about the rallies set for 160-plus nations and all 50 U.S. states.

"Yet those moments are there when we need to do things that are tough, like this Keystone XL fight," he added. "More and more people are beginning to realize that."

Indeed, the positive flavor of tomorrow's rallies is expected to turn to acrimony next week as the State Department begins a round of public hearings in the six states that the 1,700-mile pipeline would cross on its way from western Canada to Gulf Coast refineries.

Environmentalists fired a first strike yesterday in releasing internal State Department emails obtained under open-government laws that show a lobbyist for Keystone XL's sponsor who previously worked for Secretary of State Hillary Rodham Clinton offering her agency frequent help. A final ruling on the pipeline from the department is expected before 2012, though the agency signaled strong prospects for its approval in a favorable environmental review released last month (Greenwire, Aug. 26).

While greens cited those emails in doubling down on charges that the State Department is biased in favor of a permit for the pipeline, business interests and oil companies are preparing an equally high-profile case for the XL line timed to the week of public hearings.

In a first emblem of that effort, U.S. Chamber of Commerce President Tom Donohue today offered hosannas for Keystone XL in a speech to the Global Business Forum in Canada. Deeming "an abundant and affordable supply of energy" essential to North American growth, Donohue called U.S.-Canada ties "the bedrock of that foundation.

"The United States has a choice: It can secure access to a stable and reliable supply of oil from Canada -- where human rights and the environment are protected -- or it can continue to be overreliant on imports from nations that do not share our interests or values," Donohue said.

In the final leg of the marathon clash over Keystone XL, the major arguments made by both sides have shifted little.

Oil and gas interests and the Canadian government, joined by business lobbies such as the U.S. Chamber and several major unions, tout the project as a job creator that would lock in fuel imports from a stable ally. Conservationists, who have enlisted liberal groups and concerned residents in the states XL would cross, blast the pipeline as a risky guarantor of increased emissions and harm to wildlife.

This week's public hearings on the pipeline include two each in Nebraska and Texas as well as one event each in South Dakota, Kansas, Oklahoma and Montana. A final hearing in downtown Washington, D.C., is set for Oct. 7.

Before the first State Department hearing starts Monday, however, Canadian environmentalists are planning to launch a civil anti-Keystone XL protest of their own in Ottawa that McKibben said could top, "per capita," the two-week White House sit-in he organized last month. Those demonstrations yielded more than 1,200 arrests.

A U.S. show of force that could top that Canadian effort, meanwhile, is in the works for Nov. 6, to mark one year before the 2012 election. Environmental activists are planning an event that would encircle the White House with large numbers of protesters, McKibben said.