The United States appears on the brink of ending a four-decade ban on most exports of crude oil, which would mark an abrupt end to a years-long fight triggered by the domestic shale boom. If it passes both the House and the Senate, the measure to keep the government funded through September would be difficult for President Barack Obama to veto. Allowing oil exports would be a win for the U.S. oil industry and Republicans, who had argued that the ban was a relic of the 1970s Arab oil embargo.