The Senate is set to vote today on a bill to approve the Keystone XL oil pipeline after the House took similar action last week. President Obama has signaled he may veto the measure backed by Louisiana Democratic Sen. Mary Landrieu, who faces a tight runoff for re-election. On Monday, protesters rallied outside Landrieu’s home holding a sign that read “Sen. Landrieu: If you’re not a climate denier, don’t vote like one.” The pipeline would carry carbon-intensive tar sands oil from Alberta, Canada, to the U.S. Gulf Coast, passing through states including South Dakota, where it would run through the Rosebud Sioux Reservation. Rosebud Sioux President Cyril Scott has vowed to defend the reservation’s borders against the pipeline, which he calls an “act of war against our people.”