Hillary Clinton appeared on The Tonight Show with Jimmy Fallon on September 16, 2015. Photo from Facebook

Democratic presidential candidate Hillary Clinton broke her silence on the Keystone XL Pipeline and announced her opposition to the controversial project on Tuesday.

Clinton initially refused to answer questions about the multi-state pipeline because she had played a role in the review process as Secretary at the Department of State. But she believes the project is not in the best interests of the nation.

"Time to invest in a clean energy future—not build a pipeline to carry our continent's dirtiest fuel across the US," Clinton said on Twitter. "I oppose Keystone XL."

Clinton's announcement isn't much of a game-changer because her Democratic opponents -- Sen. Bernie Sanders of Vermont and former Maryland governor Martin O'Malley -- already stated their opposition. On the other hand, all of the Republican presidential candidates support the pipeline.

The State Department has been coordinating review of the project since TransCanada, a Canadian firm, submitted its cross-border permit application in September 2009. A final decision rests with President Barack Obama, who has said he will make one before he leaves office in January 2017.

Tribes have been fighting the project due to concerns about treaty lands, water, health and safety. Environmental groups also oppose the pipeline.

Get the Story:
Hillary Clinton says she opposes Keystone pipeline (The Washington Post 9/22)
Clinton’s Keystone move says more about her primary problems than anything else (The Washington Post 9/22)
Hillary Clinton Says She Opposes Keystone Pipeline (The New York Times 9/22)

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