Republicans, as well as a few Democrats, have long been frustrated by the Obama administration’s refusal to approve the Keystone XL pipeline. But the president’s decision to delay the project once again has pushed the issue toward a tipping point. In the Senate, more Democrats have joined pro-pipeline forces, and it’s entirely possible Congress will soon — perhaps as early as next week — take the matter into its own hands and force approval of the project.

On Thursday morning, Democratic Sens. Kay Hagan and Jon Tester agreed to co-sponsor a bipartisan bill by Republican Sen. John Hoeven and Democratic Sen. Mary Landrieu that would give pipeline company TransCanada the go-ahead to start work. Another Democrat, Sen. Mark Warner, signed on in the weeks after the State Department’s January determination that the pipeline would have minimal environmental impact. And seven other Democratic senators — Mark Pryor, Claire McCaskill, Mark Begich, Joe Manchin, Heidi Heitkamp, Joe Donnelly, and John Walsh — were already co-sponsors. In all, 11 Senate Democrats, some of them facing tough re-election campaigns this fall, have put their names on the pro-Keystone bill.