Hercules Taffs (born 1920), WWII veteran and Governor of Tennessee since 1970. As Governor, he implemented free textbooks for public schools, decreased the state property tax, championed small businesses, expanded Medicaid, repealed the state's right-to-work law and cracked down on riots and disorder.
Taffs narrowly defeated Jerry Brown and Mo Udall for the Democratic nomination on a populist platform that promised "real, positive and immediate" change for the American people, and relentlessly fighting corruption at all levels. He also supported expanding Medicare to cover every American, a small business tax credit, hawkish foreign policies, repealing the Taft-Hartley Act, middle-class tax cuts, energy independence, creating a Department of Education, limited steps on gun control, and higher government spending together with lower interest rates. Walter Mondale was his running mate.
He'd have lost most of the South.
He might have won MI, CA, and NJ.
He'd have lost the Deep South, FL, and VA. AR, TX, TN, and NC would all be tough.