Exxon Mobil Corp. (XOM) ’s push to export U.S. oil overseas is facing a new obstacle: falling gasoline prices. A flood of new oil from Texas to the Great Plains has swamped refineries, driving down prices at the pump 10 percent since March, while global oil prices have hovered at about $107 a barrel. That suggests the world crude market is having waning influence on U.S. gasoline, which instead is beginning to track lower-priced domestic oil. U.S. supplies are having a greater impact because they’re making up a bigger part of the gasoline market, supplying about 53 percent today, compared with 34 percent less than three years ago. As cheaper oil translates to cheaper gasoline, Exxon and ConocoPhillips will have a tougher time convincing legislators that ending export restrictions that date back to 1970s oil shortages would benefit the nation, said Sandy Fielden, director of energy […]