U.S. Senate to vote on Keystone XL Men supporting and opposing the Keystone XL pipeline project watch speakers at a State Department hearing to consider if it is in the U.S. national interest in Washington, DC, on October 7, 2011. The pipeline would carry crude oil from Canada through nine U.S. states to Houston, Texas. WASHINGTON, March 8 (UPI) -- Senate Republicans Thursday slammed President Obama for his lobbying efforts against the Keystone XL pipeline. The U.S. Senate planned to vote as early as Thursday afternoon on a Republican amendment to approve the controversial pipeline that would move oil recovered from tar sands projects in Alberta, Canada, to southern U.S. refineries. The vote was expected to be close, with Politico reporting the president was actively courting Democrats to oppose Republican Sen. John Hoeven's pro-Keystone amendment to the transportation bill. CNN said some Democrats from oil-producing states who are up for election support the pipeline but are hesitant to go against the president's wishes, sources told CNN. Senate Minority Leader Mitch McConnell accused the president of trying to block "the biggest private-sector job-creation project in our country." At a moment when millions are out of work, gas prices are literally skyrocketing and the Middle East is in turmoil, we've got a president who is up making phone calls trying to block a pipeline here at home. It's really almost unbelievable," McConnell said Thursday during his opening remarks on the Senate floor. Critics question the proposed job numbers for the project and environmental groups are concerned about the environmental impacts of both the pipeline and the tar sands oil, which is the dirtiest type of crude oil. The Senate measure needs 60 votes to pass.