Gerald Herbert/AP

Senator Mary Landrieu sure is moving fast to embrace her new Republican overlords. She just might not have the chance work with them.

Facing a run-off election in three weeks to hold onto her seat in Louisiana, the woman who is now the most endangered Democrat in America raced to the Senate floor on Wednesday—shortly after it reopened following last week's election—to call for an immediate vote on a top GOP priority: approval of the Keystone XL oil pipeline. "I want to say yes to Majority Leader Mitch McConnell," Landrieu said. "The time to start is now. The public has clearly spoken."

The third-term Democrat gave McConnell, currently the minority leader, a promotion: He won't actually become majority leader until January—and if Landrieu doesn't defeat Representative Bill Cassidy on December 6, she won't be there to see it. Hailing from a state where the oil-and-gas industry is critical to the economy, Landrieu has long been a big booster of the Keystone project and has repeatedly called on the Obama administration to approve it. Republicans have promised to take up legislation demanding its construction when they take the majority, but Landrieu wants to take home a trophy in a race she is expected to lose.

Substituting the Senate floor for a campaign hall, Landrieu dared Republicans to block a vote on a bill they wholeheartedly support, and she said Keystone's passage during the lame-duck session of Congress would send a signal to the nation that the Senate had heard the voters last Tuesday. "It is a symbol of moving past gridlock," she said. "It is a deliverable on promises we have made."

Landrieu barely referenced her own looming election, and with no apparent sense of irony, she described her maneuver as being solely about policy, not any campaign. "Politics has to be set aside," she said. "Gamesmanship has to be set aside."

But gamesmanship was exactly what Landrieu was doing, and before she had even finished her speech, Republicans in the House made their own move. They announced they would call up a Keystone bill authored by Landrieu's opponent and pass it through the chamber on Thursday. A spokeswoman for the National Republican Senatorial Committee, Brook Hougesen, dismissed Landrieu's gambit as an act of desperation:

"After years of ineffectiveness, this latest Hail Mary is yet another reminder that Mary Landrieu has failed Louisianans for years. Voters deserve a senator that doesn't just show up in the 11th hour for political benefits, but will fight every day to create good jobs and economic opportunity for Louisiana."

Whether the legislation actually will land on President Obama's desk or is merely consigned to the overflowing dustbin of political show votes is unclear, but the episode made for a dramatic afternoon on Congress's first day back in the Capitol.

For Landrieu, the political urgency was genuine: Polls taken before last Tuesday had shown Cassidy winning a run-off handily, and Democrats have canceled advertising they had planned on Landrieu's behalf. "There's always going to be tomorrow," she bemoaned, mocking those who have supported Keystone delays. For her career in the Senate, that may not be true.