Chevron Corp., which expects to be on the losing end of a long-running environmental lawsuit in Ecuador, is turning its attention to fighting the expected multibillion-dollar verdict in the U.S. The plaintiffs in the case, residents of Ecuador's oil-producing Amazonian rainforest, are seeking to hold Chevron responsible for environmental contamination they say was caused by Texaco, which…was bought by Chevron in 2001…Chevron denies the allegations, arguing that…a $40 million cleanup effort in the 1990s resolved any environmental liability the company had there, and that any remaining problems are the responsibility of Petroecuador, the state-run oil company that took over Texaco's operations.