President Roosevelt refused to give a definitive statement as to his willingness to be a candidate again, and he even indicated to some ambitious Democrats, such as James Farley, that he would not run for a third term and that they could seek the Democratic nomination. However, as Nazi Germany swept through Western Europe and menaced the United Kingdom in the summer of 1940, Roosevelt decided that only he had the necessary experience and skills to see the nation safely through the Nazi threat. He was aided by the party's political bosses, who feared that no Democrat except Roosevelt could defeat the popular Willkie. At the July 1940 Democratic Convention in Chicago, Roosevelt easily swept aside challenges from Farley and John Nance Garner, his Vice-President. Garner was a Texas conservative who had turned against Roosevelt in his second term because of his liberal economic and social policies. As a result, Roosevelt decided to pick a new running mate, Henry A. Wallace from Iowa, his Secretary of Agriculture and an outspoken liberal. That choice was strenuously opposed by many of the party's conservatives, who felt Wallace was too radical and "eccentric" in his private life to be an effective running mate (he practiced New Age spiritual beliefs, and often consulted with the controversial Russian spiritual guru Nicholas Roerich). But Roosevelt insisted that without Wallace on the ticket he would decline re-nomination, and when First Lady Eleanor Roosevelt came to Chicago to vouch for Wallace, he won the vice-presidential nomination with 626 votes to 329 for House Speaker William B. Bankhead of Alabama. In the months leading up to the opening of the 1940 Republican National Convention in Philadelphia, Pennsylvania, the Republican Party was deeply divided between the party's isolationists, who wanted to stay out of World War II at all costs, and the party's interventionists, who felt that the United Kingdom needed to be given all aid short of war to prevent Nazi Germany from conquering all of Europe. The three leading candidates for the Republican nomination - Senator Robert A. Taft from Ohio, Senator Arthur H. Vandenberg from Michigan, and District Attorney Thomas E. Dewey from New York - were all isolationists to varying degrees. Taft was the leader of the conservative, isolationist wing of the Republican Party, and his main strength was in his native Midwestern United States and parts of the Southern United States. Dewey, the District Attorney for Manhattan, had risen to national fame as the "Gangbuster" prosecutor who had sent numerous infamous Mafia figures to prison, most notably Lucky Luciano, the organized-crime boss of New York City.