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Citing anonymous sources, the trio report carbon emissions aren't likely to be greatly affected by a decision because the Alberta oil sands, whose crude the pipeline would be transporting, are still going to be developed anyway.
The Supplemental Environmental Impact Statement could be released as soon as tomorrow, they write.
Once it's published, President Obama will then have to determine whether approving the project is in the national interest.
There is no formal deadlines for that decision.