A power broker in the St. Louis
Democratic Party allied with Senator
Bennett Clark, Hannegan helped save the political career of
Harry S. Truman in 1940 following the
tax fraud conviction of Truman's ally, Kansas City boss
Tom Pendergast. Hannegan supported Truman for re-election to the
U.S. Senate when he was challenged in the Democratic primary by Governor
Lloyd C. Stark and
Maurice M. Milligan, who both sought credit for bringing down Pendergast. Truman re-won the seat with increased support in St. Louis, particularly from
Catholic neighborhoods in which Hannegan wielded considerable influence. In his second term, Truman achieved national prominence by chairing a Senate committee investigating government waste in defense contracts. When
Franklin D. Roosevelt offered Truman the position of DNC chairman, Truman declined but recommended Hannegan. at the Oval Office, in 1946. In 1944, Roosevelt appointed Hannegan, who had been the Collector of Internal Revenue in St. Louis, to the DNC after testing him by asking for his help with his
income tax return. As Democratic chairman, Hannegan was responsible for brokering the deal that made Truman Roosevelt's running mate
that year. Shortly before the
1944 Democratic National Convention, Roosevelt famously sent Hannegan a letter stating he would be "happy to run with" either Truman or
Supreme Court Justice
William O. Douglas. Vice President
Henry A. Wallace nearly won the nomination, but Hannegan worked feverishly to secure Truman's nomination. Hannegan later joked he wanted his tombstone inscribed with the words "Here lies the man who stopped Henry Wallace from becoming President of the United States." Though plagued with ill health for much of his tenure as party chairman, Hannegan emphasized voter turnout efforts in Roosevelt's 1944 re-election campaign and prevented an upset by
Thomas Dewey, who won a surprising 46 percent of the popular vote that year. He promoted a
liberal policy agenda for the national party and was a strong advocate of
labor unions. Hannegan stepped down as chairman after Democrats suffered congressional losses in the 1946 midterm elections, but his ideological focus at the helm of the party contributed to Truman's upset win in the presidential election of 1948, and influenced his
Fair Deal proposals. ==Death==