Regulating interstate commerce is one thing that is referred to in the constitution as a federally enumerated power. The Keystone pipeline is exactly such. Lets let Obama play where he belongs.
Your suggestion was not regulation of interstate commerce.
It was to supply a specific additional tax to one single pipeline not applied to all the other pipelines that already bring Canadian Crude into the US.
Why does TransCanada’s pipeline, but only one of theirs, get a special tax that does not apply to Enbridge’s or others? Why would such a tax not apply to trains and trucks?
Quit trying to use the Federal Government to pick winners and losers in private industry.