The Democratic Party is moving faster and more aggressively than in previous election years to dig up unflattering details about Republican challengers. In House races from New Jersey to Ohio to California, Democratic operatives are seizing on evidence of GOP candidates' unpaid income taxes, property tax breaks and ties to financial firms that received taxpayer bailout money. In recent weeks, the Democratic Congressional Campaign Committee has circulated information to local reporters about Republican candidates in close races. Among the claims: -- That Jim Renacci of Ohio once owed nearly $1.4 million in unpaid state taxes. -- That David Harmer of...