Roughly half of our oil imports come from politically unstable Middle Eastern nations.
By increasing U.S. oil production (from off shore drilling, from natural gas fields, and from shale oil fields) we could cut our oil imports roughly in half.
By using U.S. resources, and creating U.S. jobs, we could end our dependence on oil imported from unstable, risky regimes. What's not to like? Why is this such a hard thing to approve?