Green groups came out early — and hard — for President Barack Obama this season.

They threw in money from the start. They drummed up big-name endorsements when other liberal groups hung back. And they’ve joined the ranks of campaign foot soldiers.

So environmentalists should be excited to see their guy ahead in the polls — a sign that their hard work is paying off.

Instead, they’re grappling with a tough reality: Even a win could be setting themselves up for a colossal loss early next year.