A runoff election in Louisiana is propelling Keystone XL legislation to the United States Senate floor Tuesday.

Behind the pipeline push is Democrat Sen. Mary Landrieu. Unlike many Democrats, who oppose the pipeline for environmental reasons, the Louisiana senator backs the project and says it will have economic benefits.

The position is part of Landrieu’s moderate platform. She is trying to appeal to Louisiana voters as she fights to keep control of her senate seat after failing to win a majority in the Nov. 5 midterm elections. As the Dec. 6 runoff election that will decide her fate approaches, Landrieu is now pushing a pro-Keystone bill.

The House passed the Keystone XL bill Friday, and now the Senate is scheduled to vote on the bill on Nov. 18.

Though the Republican-controlled House has approved pro-pipeline legislation in the past, Keystone XL bills have never made it through the Democrat-controlled Senate. But Landrieu is hopeful that Tuesday’s vote will be different.

The 45 Republicans in the Senate are almost guaranteed to all vote in favour of the pipeline bill, but the Democrat votes are more uncertain, with the exception of Landrieu.

Many Democrat voters oppose the pipeline, which would carry bitumen from Hardisty, Alta., to Steel City, Neb.

But after losing the Senate majority on Nov. 5, Landrieu's Democrat colleagues could also decide to help her hang onto her seat.

Sixty votes are necessary to force the bill past the Senate filibuster and into Obama’s lap.

The U.S. president, meanwhile, has the power to veto the bill, unless two-thirds support (67 votes) is secured in the Senate. On Friday, Obama hinted that he may exercise that power, saying the pipeline would benefit Canadian oil without reducing U.S. gas prices.

Senate control shifts in January

In January, the Republicans will officially gain control of the Senate as midterm winners assume their seats.

The Keystone XL decision could have major economic and political repercussions both in the United States and in Canada.

The Canadian government supports the pipeline, which is predicted to export 700,000 barrels of bitumen a day and create 9,000 jobs. But Obama has repeatedly put off making a decision on the project.

For more on Keystone XL, watch CTV's Question Period, Sunday at 11 a.m. ET