Thad Cochran, a courtly Mississippi Republican who cultivated his constituents for 45 years as a congressman and United States senator with traditional catfish fries, Southern charm and billions of dollars in federal pork-barrel largess, died on Thursday in Oxford, Miss. He was 81.

His death was confirmed by the office of Senator Cindy Hyde-Smith, who replaced him in the Senate after he resigned in 2018 because of health issues. The cause was not specified.

With his homespun politics, moderation on racial issues and business-oriented conservatism, Mr. Cochran may have seemed out of place on the modern Washington merry-go-round. But he outlasted almost everyone, winning three terms in the House of Representatives and seven in the Senate.