 Despite this mixed record, Roosevelt believed some Democratic partisans hoped to nominate Barkley for president at the 1940 Democratic National Convention, but the German invasion of Poland on September 1, 1939, deepened his resolve to seek a third term.Barkley disagreed with Roosevelt's selection of Agriculture Secretary Henry A. Wallace as his running mate; Libbey felt that "there is enough evidence from Barkley's tortuous private and public statements about the qualifications of Wallace to infer that Barkley wanted the vice presidency for himself", although he did not promote this idea to Roosevelt.Barkley was chosen permanent chairman of the convention; chants of "We want Roosevelt" interrupted his July 16 speech for 20 minutes, indicating that he had created a popular mandate for Roosevelt's renomination, which occurred the next day.