NASHVILLE — Ned McWherter, a onetime factory worker who became a millionaire businessman and two-term Democratic governor after two decades as a legislator, died Monday afternoon. He was 80. Madelyn Pritchett, his longtime assistant, said McWherter died after a battle against cancer at Centennial Hospital in Nashville where he had been taken Saturday. McWherter, of Dresden, was governor from 1987 to 1995, following 20 years in the Legislature — and 14 as House speaker. He also was political adviser to Bill Clinton during his presidency. A child of sharecroppers, he became a millionaire through various business enterprises before entering politics.