He doesn't have to veto the bill to stop the pipeline. All the bill does is require that the regulatory agencies do their environmental evaluation within 60 days. At the end of the 60 days, if they haven't had time to complete their evaluation, they wouldn't be able to approve the pipeline, and if the pipeline doesn't get approval by the relevant agencies, Obama doesn't have to lift a finger or say a word to stop it.
If you take your car in to be smogged, they tell you it will take a half hour and you tell them you have to leave in five minutes, if you leave in five minutes, before the smog test is finished, your car won't pass, and you won't be able to renew registration for your car. The Republicans are pretty much doing the same thing to the pipeline. Idiots.
You should have put another option in the poll, Mr. P. He'll sign, but the pipeline won't be approved.