Governor In
1938, he ran for governor of Texas as a
Democrat. O'Daniel's campaign hailed his flour and the need for pensions and tax cuts. He promised to block a
sales tax and raise pensions. O'Daniel won the Democratic primary election with 51 percent of the ballots over twelve opponents. In office, he seemingly went against his campaign promise by proposing a new transaction tax, which was voted down by the
Texas Legislature. Despite this position change, he remained personally popular and handily won
re-election in 1940. In both elections, his main competition came from
Texas Railroad commissioner
Ernest O. Thompson, the former mayor of
Amarillo.
U.S. Senate O'Daniel ran for the United States Senate in the
1941 special election following the death of
Morris Sheppard. He defeated
Lyndon Johnson by 1,311 votes in one of the most controversial elections in state history. As a result of this experience, in the
1948 election, Johnson prepared for a close runoff by arranging for his supporters who controlled votes, including
George Parr, to withhold their final tallies until the statewide results were announced. As a senator, O'Daniel was ineffective, and most of his legislation was defeated. He endorsed the anti-
Roosevelt Texas Regulars in the
1944 presidential election. Elected to a full term in 1942, O'Daniel refused to run for another term in 1948. ==Later career==