The best way to tell that Hillary Clinton's opposition to the Keystone XL pipeline is a political winner is to look at the reaction of her rivals for the Democratic presidential nomination.
They can't blame her for agreeing with them, so they're pointing out that they were there first.
Here's Bernie Sanders:
As a senator who has vigorously opposed the Keystone pipeline from the beginning, I am glad that Secretary Clinton finally has made a decision and I welcome her opposition to the pipeline. Clearly it would be absurd to encourage the extraction and transportation of some of the dirtiest fossil fuel on the planet.
And here's former Maryland Gov. Martin O'Malley, who noted Clinton has been later to the game on some other matters, too:
Leadership is about stating where you stand on critical issues, regardless of how they poll or focus group. On many of these issues, I staked out positions and got things done—even when they were politically unpopular. That’s what’s at stake in this election: the difference between conviction and convenience, and the gulf between actions and words.
In other words, there's no room on the left to criticize her for the decision. Clinton, who was Secretary of State when the Keystone decision was first making its way through the Obama administration, telegraphed last week that she planned to make an announcement "soon." She said she was "putting the White House on notice" that she couldn't wait any longer, portraying her reticence as deference to the administration.
And let's face it, the idea that Republican voters would cast ballots for Clinton because she was for the pipeline — or that Democrats or independents would vote against her because she opposes it — is pretty laughable.
Several of Clinton's top donors, including Tom Steyer and Susie Tompkins Buell, are active in the environmental movement, and they have wanted her to come out against Keystone for some time. It's an issue that matters a lot to that segment of the Democratic Party, and coming out against the pipeline takes a wedge issue away from Clinton's current opponents — and perhaps Vice President Joe Biden, if he runs.
While most Republicans approve of the deal, it doesn't rank with the economy and national security as the top issues that will turn votes in a general election. The bottom line: It matters to Clinton only in the Democratic primary, and she can only benefit from siding with the environmental movement.