Final answer:
Truman felt that the results of the 1948 election gave him a mandate to pass social reform due to a shift in public opinion reflected in the election results.
Step-by-step explanation:
Truman felt that the results of the 1948 election gave him a mandate to pass the social reform that he was previously unsuccessful in achieving because the election results reflected a shift in public opinion. Republicans attacked Truman during the congressional elections of 1946, which led to a frustrated electorate questioning the new president's principles. Truman then used a strategy similar to the Republicans in the 1948 election, appealing to the frustration of voters and highlighting his support for New Deal-like programs that were blocked. This strategy worked for Truman, and he ultimately won the election. Overall, the election revealed a changing public opinion and a desire for progress in areas such as race, the Cold War, and social programs.