The former senator and envoy says it will likely take a major scandal to trigger a change. PORTLAND - Like most Americans, former U.S. Sen. George J. Mitchell said, he tends to look at the past through rose-tinted glasses. But even with that in mind, partisanship in Washington wasn't as bad when he was in the Senate as it is now, Mitchell said Wednesday morning. Mitchell said the structure of the political system leads to the heightened partisan atmosphere -- and that's responsible for the record low approval rate of 9 percent for Congress in a recent poll. "It's worse...