Thomas did not run for re-election in 1881, and in 1882, he waged a
campaign for nomination to Congress, from
Wisconsin's 7th congressional district. His principal opponent was believed to be
Gideon Hixon, who had the support of delegates from La Crosse County, but after 29 ballots at the Republican 7th district convention, the delegates broke in favor of
Cyrus M. Butt, of Viroqua. Butt went on to lose the general election to Democrat
Gilbert M. Woodward. Two years later, Thomas made another run for congress. This time, he won the nomination on the first ballot at the convention. He went on to defeat Woodward in the general election with 52% of the vote. He was subsequently re-elected in 1886 and 1888, serving in the
Forty-ninth,
Fiftieth, and
Fifty-first congresses. During the 51st Congress, Thomas was chairman of the
House Committee on War Claims. He was defeated seeking a fourth term in
1890, in the wave election that saw Democrats claim 8 of Wisconsin's 9 congressional seats. After leaving office, he resumed his legal career with his old partner, Judge C. S. Fuller. Fuller, however, committed suicide in 1897. In 1898, Thomas accepted the Republican nomination for another term as district attorney of Crawford County, and was elected in the Fall. During his final term as district attorney, Thomas suffered from
Bright's disease. His health continued to deteriorate after he left office in January 1903. He died at his home in Prairie du Chien on October 24, 1904. At the time of his death, he was described as the oldest member of the
State Bar of Wisconsin. ==Personal life and family==