President Barack Obama’s veto of a bill approving the controversial Keystone XL pipeline is kicking off a new round of denunciations from critics as well as support from Hollywood A-listers, including this week’s best-actress Oscar winner Julianne Moore.

Obama vetoed a bill, passed by the GOP-controlled Congress Feb. 11. and delivered to the White House Tuesday afternoon, to allow a 1,179 mile pipeline from Hardisty, Alberta to Steele City, Nebraska. His veto, only the third of his presidency, came as no surprise. White House officials had indicated he would take such action to assert his presidential powers.

“Because this act of Congress conflicts with established executive branch procedures and cuts short thorough consideration of issues that could bear on our national interest — including our security, safety, and environment — it has earned my veto,” Obama said in his veto message to Congress. Senate Majority Leader Mitch McConnell, a Kentucky Republican, said he would hold a vote to override the veto, but neither the House nor the Senate appears to have the two-thirds majority needed for an override.

The pipeline, first proposed by Calgary-based TransCanada in 2008, has become one of the most divisive issues of Obama’s administration. Opponents see it as a test of the president’s commitment to the environment, arguing it would promote extraction of viscous Canadian oil that emits more greenhouse gases when burned than conventional crude. Proponents, including GOP lawmakers and the fossil fuel industry, say it would create jobs and bolster North American energy security by securing delivery of Canadian crude.

Even before Obama vetoed the bill, conservatives began denouncing the expected move. The conservative group Americans for Prosperity, partly funded by the billionaire libertarian brothers Charles and David Koch, launched a media campaign to criticize it.

“This veto proved once again that it’s politics as usual here in Washington.,” said Jack Gerard, president of the American Petroleum Institute. “Instead of standing with 72 percent of Americans, including a majority of Democrats, who support the pipeline, this decision continues us down the path of indecision and delay.”

Environmentalists hailed the veto as a huge victory. “Today, the pen was mightier than the pipeline,” said Anna Aurilio of the advocacy group Environment America. “President Obama deserves credit for standing up to Big Oil,” she said, adding that it’s time to stop global warming and Keystone would only accelerate it.

Also backing the president was a diverse coalition of more than 100 high-profile individuals that include actors Julianne Moore, Mark Ruffalo, Robert Redford, Alex Baldwin. In a “Unity Letter” sent to the White House, the signatories called Keystone a “classic boondoggle” that won’t create many jobs but will pose risks to health and safety and only benefit “a handful of rich oil companies.”

Obama’s veto is hardly the end of the Keystone debate. The president could still approve the project although he’s made critical comments about its environmental impact. Because it crosses an international border, Keystone has undergone lengthy environmental reviews by the State Department.

Congressional Republicans have said they’ll continue to fight for Keystone, possibly by attaching provisions that force its approval to must-pass spending bills. Also, TransCanada says it remains committed to the project, even though it faces other obstacles that go way beyond Washington politics. (See related story: “Two Reasons Why Obama’s Veto Won’t Decide Pipeline.”)