WASHINGTON (Reuters) - Republican-backed bills that would clear away environmental constraints for building new U.S. oil refineries and drilling in an Alaskan wildlife refuge were expected to win approval in the U.S. House of Representatives on Wednesday. But both measures were largely symbolic with virtually no chance of approval this year by the U.S. Senate, according to lobbyists and congressional aides. Faced with voter concern about record-high gasoline prices in recent weeks, House Republicans also sought to blame Senate Democrats for blocking a broad energy bill that would be the first major overhaul of U.S. energy policy in a decade....