Believing strongly in the democratic process as these groups did, this attack was mounted within the framework of the legal system. The N.A.A.C.P. came to be the cutting edge of the campaign. In particular, the Legal Defense Fund of the N.A.A.C.P. and the small group of intelligent, dedicated Negro lawyers whom it financed, spearheaded the attack. It was clear that the legal system itself supported the position of Southern racists. Most Afro-Americans in the South could not vote, and Southern senators were in a position to sabotage any attempt to change the system through the legislative process. They were chosen through a white electorate, and Afro-Americans in the South could do little about that. Even if a favorable majority in Congress stemming from the North and West could be established, the one-party system in the South meant that Southern Senators were continually reelected and, therefore, had Congressional seniority. Consequently, they controlled most of the comittees and were thereby in virtual control of the legislative process itself. Although the courts had usually interpreted the Constitution so as to support segregation, much of that document's language supported democratic and equalitarian principles. If the courts could be persuaded to understand the Constitution differently, legal segregation might well be found to be unconstitutional. The judicial system to some degree reacts to popular pressure and events, and it too was influenced by the need to justify American democracy to the rest of the world. The N.A.A.C.P. had already mounted a broad, concerted attack against legal segregation before the Second World War. When Walter White defeated W. E. B. DuBois in a struggle for leadership, he confirmed the Association's emphasis on striving for an integrated society. The number of white and middle-class black supporters of the N.A.A.C.P. grew, and its treasury prospered. The Association chose to concentrate its efforts on a gradual, relentless attack against segregation through the courts. Believing that education was an all-important factor in society, it decided that school desegregation should become the major target. Thurgood Marshall was the master strategist in the school desegregation campaign. He decided that the attack should be a slow, indirect one. Most Southern school systems, although they had developed two separate institutions, had not established separate graduate and professional facilities for Negroes. Marshall decided to attack the school question on the graduate, professional, and law-school level. First, Southerners did not seem as frightened about racial mixing on the graduate school level, and second, the cost of developing separate graduate and professional schools for a handful of Negro students, it was reasoned, would be prohibitive.