The reason you have heard of the Keystone XL pipeline is because of the environmental movement. Several years ago, the green group (named for an aspirational concentration of carbon dioxide in the atmosphere) and other groups seized upon the project, which would shunt a form of oil from Alberta to the Gulf Coast, as a symbol of the sort of thing the country should avoid if it wants to curb climate change.

This week, though, Keystone XL has become a symbol for moderate Democrats like Sen. Mary Landrieu (D-La.) -- a demonstration that they can serve as the bridge between the new Democratic minority and the Republican majority in the next Congress.

"Si se puede!" Landrieu said Wednesday while pushing for the pipeline on the Senate floor, re-purposing another bit of progressive politics (this time from the United Farmworkers) in service of a project that's not very popular with the left. That's intentional. Landrieu faces a run-off against Republican Bill Cassidy next month -- and is in deep trouble. Seizing upon the pipeline as a way to shift the politics in that race, though, is almost certainly not going to work.

Landrieu was joined Wednesday by other red-state Democrats to advocate for passage of a measure that would side-step the president on granting approval to the pipeline. (Since it crosses the Canadian border, the State Department has the ability to grant or reject a permit for the project -- giving the administration an effective veto over it.) The subtext of the election was central to the floor speeches from Landrieu, Sen. Joe Manchin (D-W.Va.), and Sen. Jon Tester (D-Mont.); Manchin specifically noted how valuable Landrieu's leadership on the Senate's Energy and Natural Resources had been, reinforcing the leadership that has been one of the central arguments to her campaign.

It's clear why pushing for the project now appeals to Landrieu. Obama is against it and, in exit polls taken last week in her state, 88 percent of voters who backed her opponents said Landrieu agreed with Obama too often. Ninety-five percent of them saw their vote as a vote in opposition to Obama.

Keystone also helps Landrieu make a case on the economy, which more than half of the people who voted against her listed as their primary issue. From the floor of the Senate, Landrieu argued that the project was backed by business and labor because of the jobs it promised. She linked the pipeline loosely to the oil boom in North Dakota (a function of fracking, not pipelines), declaring that North Dakota's jump from the 36th- to the 6th-best economy in the country "is the power of this industry, and we are standing in its way." The actual economic benefits of the pipeline are much-debated, with most jobs created by the pipeline being temporary, during its construction.

"Elections have consequences," Landrieu said from the floor, referring to the midterms. "They all do. And this one does. This election has opened up a path for Keystone."

Manchin agreed, saying, "There's not a better piece of legislation to show that we heard the results of Tuesday's elections." The implication: Landrieu will be the moderate problem-solver, working between the parties.

So why won't this get her reelected? For one thing, as Landrieu herself noted, the pipeline doesn't actually come to Louisiana, but to Texas. Even if it were completed, any economic benefits would be much smaller for her state. Keystone XL itself doesn't go to Texas; a pipeline that would move oil from the XL pipeline to the Gulf Coast is already built. Meaning that even the short-term construction jobs would be outside of the region. (Nationally, support for the pipeline has dropped, though it's not clear if that's true in Louisiana.)

For another, it's not clear that there is a big moderate base in the state from which Landrieu can pull many more votes. Forty percent of those polled on Election Day were moderates, and Landrieu won 54 percent of them. The question mark is who scoops up more votes from those who voted for a candidate who didn't make the run-off. In pre-Election Day polling, Cassidy gained 14 points in a head-to-head contest, while Landrieu gained only four points. That the third-place candidate last week was tea party-backed Rob Maness suggests that Landrieu's embrace of the moderate center might not eat into the shifts predicted by the polls.

At the same time, her Democratic supporters might be dismayed to hear Landrieu say that the pipeline makes a "compelling environmental argument" -- from the standpoint that it's safer to transport oil by pipe than train or truck. True, but most environmentalists wouldn't say that's a "compelling environmental argument" (any more than they think "si se puede" should refer to pipeline-building). It's hard to say without clear polling how much support Landrieu needs from the state's not-huge progressive minority. But it seems clear she's not worried about it -- or at least knows she can't win without expanding her brand.

If the bill passes, President Obama could still veto it, which, again, would probably be helpful to Landrieu. Over the past week, TV ads supporting Cassidy have outnumbered ads supporting Landrieu by 24-to-1. The extent to which voters will even hear about Landrieu's push for Keystone isn't clear. Obama putting it on front pages wouldn't hurt.

Thanks to environmentalists, the Keystone XL pipeline serves as a decent symbol for all of the things Landrieu needs to reinforce: her history, her centrism, her commitment to the energy industry. "It's a symbol that represents American energy power," Landrieu said on Wednesday. "Let's act today."

After all, she might not have the chance to act in January.