Politics is about compromise. The majority of politicians appear to want to pass the Keystone XL pipeline deal. I would suggest that in exchange for not vetoing the Keystone XL project, the house and senate pass a bipartisan bill for you to sign that will raise the tax credit on electric vehicles from the maximum of $7,500 to $12,500 and extend that credit for 5 years with no limit on the number of new cars that it can be used on.
Doing this would allow the market to dictate what happens. You would make it very hard to not sell more electric cars with huge incentives on them (that oh by the way drive way nicer than most internal combustion engine cars) which would continue to drive down the demand for oil making future pipelines like this unnecessary. It would be a win-win.