Democrats must overhaul party, attack big business, Sanders says

By Lucia Mutikani and Doina ChiacuWASHINGTON (Reuters) - Former U.S. Democratic presidential candidate Bernie Sanders on Sunday urged a major overhaul of his party, calling for more aggressive efforts to court working-class voters and fight big businesses from Wall Street to the pharmaceutical sector.Sanders, who spoke a day after Democrats chose Tom Perez, a veteran of former President Barack Obama's administration, as their new party chairman, said it was also crucial for progressives to do mo