in the emerging craft of public opinion polling. According to historian William Manchester, "many professional pollsters...believed in what some had come to call Farley's Law." James Farley, President Franklin Roosevelt's successful campaign manager in 1932 and 1936, had stated that, in his opinion, the great majority of voters decided which candidate to support during the political conventions. The fall campaigns, Farley believed, were simply "ineffective carnivals" that swayed few voters. In 1948 many pollsters, relying on Farley's Law, believed that the election was effectively over after the Republican and Democratic Conventions, and they discounted the impact of Truman's campaigning that fall. Manchester noted that "Gallup's September 24 report foresaw 46.5% for Dewey to 38% for Truman. His last column, appearing in the Sunday papers two days before the election, showed Truman gaining sharply – to 44 percent – and the interviews on which it was based had been conducted two weeks earlier. The national mood was shifting daily, almost hourly." After the election, a study by the University of Michigan revealed that "14% of Truman's voters, or 3,374,800, had decided to vote for him in the last fortnight of the campaign." Gallup and Roper also did an analysis of the votes; they "learned that one voter in every seven (6,927,000), made up his mind in the last two weeks before the election. Of these, 75 percent picked Truman", which was more than his margin of victory over Dewey. "Using either the Michigan figures or Gallup-Roper's, one finds that some 3,300,000 fence-sitters determined the outcome of the race in its closing days – when Dewey's instincts were urging him to adopt Truman's hell-for-leather style and slug it out with him, and when he didn't because all the experts told him he shouldn't." The key states in the 1948 election were Ohio, California, and Illinois. Truman won each of these states by less than 1 percentage point; they gave him a total of 78 electoral votes. Had Dewey carried all three states - which would have required a shift of just 29,000 votes - he would have won the election in the Electoral College despite losing the popular vote by 2.13 million votes (or 4.36%). If Dewey had won any two of the three, no nominee would have reached the 266 electoral votes required for election, and the Dixiecrats would have succeeded in their goal of forcing the election into the House