MADISON, Wis. — Democratic U.S. Senate candidate Mandela Barnes raised $20.1 million in the three-month period that ran through September, his campaign reported. Incumbent Ron Johnsn had yet to file his legally required financial statement. For Barnes the new report showed a dramatic increase spurred by his primary election victory in August. Barnes had raised about $6 million through the end of June. His campaign did not disclose how much cash was on hand. It did say the donations came from 230,000 individuals and that none was corporate PAC money. A thrust of Barnes’ campaign has been that Johnson is beholden to big-money corporations that haved funded his three campaigns for the Senate and influenced his votes against the interests of ordinary people.