Every election has its holdouts who predict polling and conventional wisdom leading up to the big vote is way off. This year, the optimism caucus has to work overtime for Democrats. With less than a week to go until Election Day, most Democrats are bracing for potentially huge defeats — including losing one or both chambers of Congress — but some in the party aren’t willing to concede anything just yet. “I don’t believe the GOP is headed for any kind of a wave,” said Angelo Cocchiaro, a Democratic Party activist based in Virginia. “The polls show tight races nationwide....