Thus, Truman's election confirmed the Democratic Party's status as the nation's majority party. Democratic candidates: On July 12, the Democratic National Convention convened in Philadelphia in the same arena where the Republicans had met a few weeks earlier. Spirits were low; the Republicans had taken control of both houses of the United States Congress and a majority of state governorships during the 1946 mid-term elections, and the public opinion polls showed Truman trailing Republican nominee Dewey, sometimes by double digits. Furthermore, some liberal Democrats had joined Henry A. Wallace's new Progressive Party, and party leaders feared that Wallace would take enough votes from Truman to give the large Northern and Midwestern states to the Republicans. Conservatives dominated the party in the South, and they were angered by the growing voice of labor unions and black voters in the party outside the South. The hope that Truman would reverse course had faded by 1947, when he vetoed the Taft-Hartley Law, which would have helped control union power. Truman's appointment of a liberal civil rights commission convinced Southern conservatives that to re-establish their voice they had to threaten third-party action to defeat Truman in 1948. Truman was aware of his unpopularity. In July 1947, he privately offered to be Eisenhower's running mate on the Democratic ticket if MacArthur won the Republican nomination, an offer which Eisenhower declined. Truman's offer to Eisenhower did not become public knowledge during the campaign. As a result of Truman's low standing in the polls, several Democratic party bosses began working to "dump" Truman and nominate a more popular candidate. Among the leaders of this movement were Jacob Arvey, the head of the powerful Cook County (Chicago) Democratic organization; Frank Hague, the boss of New Jersey; James Roosevelt, the eldest son of former President Franklin D. Roosevelt; and liberal Senator Claude Pepper from Florida. The rebels hoped to draft Eisenhower as the Democratic presidential candidate. On July 10, however, Eisenhower officially refused to be a candidate. There was then an attempt to put forward Supreme Court Justice William O. Douglas, but Douglas also declared that he would not be a presidential candidate. Finally, Senator Pepper declared his intention to challenge Truman for the presidential nomination. His candidacy collapsed when the liberal Americans for Democratic Action and the Congress of Industrial Organizations withheld their support, partly due to concerns over Pepper's attacks on Truman's foreign policy decisions regarding the Soviet Union. As a result of the refusal by most of the dump-Truman delegates to support him, Pepper withdrew his candidacy for the nomination on July 16.