Hillary Clinton knows a thing or two about the Keystone XL pipeline, but good luck trying to get her to give her opinion publicly.
She led President Obama's State Department while it endlessly scrutinized the project and once declared she was "inclined" to sign off on the pipeline. Bill Clinton has said Americans need to "embrace" the pipeline. And it's an issue near and dear to the hearts of major Democratic donors critical to her 2016 presidential plans.
But Clinton now refuses to say what she thinks about the pipeline that has ignited a contentious debate over global warming and American energy security.
Her silence frustrates environmentalists who want assurances that Clinton is on their side. But Washington's green power players have stopped short of publicly pressuring her into taking a stand, and high-profile environmentalists say it won't make much difference if Clinton breaks her silence at all.
"Of course I wish she would say something, but I don't go to bed at night worrying that Hillary Clinton isn't talking about Keystone," said Bill McKibben, the founder of grassroots environmental group 350.org, which helped elevate the issue in Democratic circles.
The latest twist in the years-long saga over Keystone arrived Tuesday when Obama vetoed legislation to approve the pipeline, a rebuke to Republicans who campaigned on the issue in 2012 and 2014.