Nevertheless, polls showed opposition to Truman's civil rights efforts. They likely cost him some support in his 1948 reelection bid against Thomas Dewey. Although Truman narrowly won, Gardner believes that his continued championing of civil rights as a federal priority cost him much support, especially in the Solid South. Southern Democrats had long exercised outsize political power in Congress, having disfranchised most blacks there since the turn of the 20th century, but benefiting by apportionment based on total population. Truman's efforts threatened other changes since numerous communities across the country had restrictive covenants that were racially discriminatory. Because of his low approval ratings and because of a bad showing in early primaries, Truman chose not to seek re-election in 1952, though he could have done so. He had been exempted from the term limitations which are imposed by the 22nd amendment.