This vote was on an amendment that would have required Canadian energy companies to pay an 8-cent-per-barrel tax for oil shipped through the proposed Keystone XL pipeline.

Sen. Ron Wyden (D-OR) offered the amendment during consideration of a bill authorizing construction of the controversial pipeline, which would connect Canada’s “tar sands” oil fields to the United States and the world market. Sen. Wyden’s amendment would have altered federal tax law to make sure the Canadian oil is actually classified as oil and, therefore, subject to an excise tax that funds clean-up efforts in the case of a spill. The Canadian oil would not otherwise be subject to the tax because it is a mixture of soil and bitumen that is mined rather than drilled. The substance can be turned into oil only through a complex process of extraction and separation.

Sen. Wyden argued that Congress should fix the “loophole,” which threatened to allow Canadian producers to ship their oil across the United States without paying into the clean-up fund. The Canadian oil is as likely to spill as American-produced oil, he said, and tax-free status would put U.S. oil producers at a disadvantage and force taxpayers to foot the bill for oil spills.

“Tar sands oil producers ought to pay into the same fund as other oil producers to clean up the spills. Because, make no mistake about it, at the end of the day, without this amendment that closes the tar sands loophole, Canadian tar sands oil will keep getting a free ride,” Sen. Wyden said.

Sen. Lisa Murkowski (R-AK), who opposed the amendment, argued that it would violate the Constitution’s requirement that revenue-raising bills start in the House of Representatives. She argued that it was good enough that the Senate had already added a non-binding statement in support of taxing the Canadian oil; senators could push the House to add the provision later on, she said.

“If we agree that we want to close this loophole, which we should do, we need to allow for the House to address this,” Sen. Murkowski said. “Otherwise … it would act as a poison pill to the Keystone XL bill.”

Even though 50 senators supported Sen. Wyden’s amendment and only 47 voted against it, the amendment was defeated because it was brought up under Senate rules that require 60 votes for passage. Voting “yea” were 45 Democrats and 5 Republicans. Voting “nay” were 47 Republicans. As a result, the Senate defeated the effort to require Canadian energy companies to pay an 8-cent-per-barrel tax for oil shipped through the proposed Keystone XL pipeline.