Sen. Claire McCaskill of Missouri could play a crucial role in approving the controversial Keystone XL pipeline this week.

Senate Majority Leader Harry Reid has indicated a vote could be held in the next few days to authorize the pipeline that would carry Canadian crude oil through the U.S. to the Gulf Coast.

McCaskill is one of the few Senate Democrats in favor of the project. During a conference call with reporters Wednesday, she argued the oil will be flowing regardless of the pipeline’s approval.

“This would be a different conversation if it wasn’t coming out of the ground, but it’s going to come out of the ground,” she said.

“Then the question is: how is it moved? Is it moved through a pipeline in Canada? Is it moved by barges and railcars through the United States or is it moved by a pipeline through the United States?” she asked. “Of all those alternatives, the pipeline is the safest, it’s the most environmentally sound and it also has the added benefit of creating jobs in the process.”

All 45 Senate Republicans are expected to vote in favor of the plan, which would then need 15 Democratic votes to overcome a filibuster. Other Democratic senators favoring the plan include Kay Hagan of North Carolina, Mary Landrieu of Louisiana, and Mark Pryor of Arkansas. If the measure does pass the Senate, the Republican-controlled House of Representatives is expected to approve the bill as well.

That could present a tough decision for President Barack Obama, who would face significant pressure from environmentalists and liberal constituents to veto the bill. The White House has delayed a decision on Keystone XL citing a court battle in Nebraska over the pipeline’s path through the state.