See the Giant Inflatable Keystone Pipeline on Mary Landrieu's Lawn

Activists placed fake pipeline at senator's D.C. home to protest Keystone XL.

“If she wants this pipeline so badly, it can go through her front yard and not any one of ours,” said Karthik Ganapathy, communications manager for 350 Action, an environmental advocacy group.

Showdown Over Keystone XL Pipeline

TransCanada CEO: 'High Probability' Keystone XL Pipeline Will Be Built

Louisiana Senate Candidates Race to Hold Lame Duck Votes on Keystone XL Pipeline

Landrieu did not immediately respond to a request for comment on the demonstration.

"Keystone XL is going to be the turning point," Tanderup added. "We either go backwards in time with Keystone XL, or we move forward and say this country is going to do what it should have been doing for several years, and work ourselves away from these dirty tar sands, and get us into that clean energy environment."

The Senate is slated to hold a vote on authorization of the pipeline on Tuesday and currently appears just one vote short of crossing the 60-vote threshold.