Give some stream of consciousness and then the answer. The Mississippi Freedom Democratic Party (MFDP) was an American political party created in 1964 as a branch of the populist Freedom Democratic organization in the state of Mississippi during the Civil Rights Movement. It was organized by African Americans and whites from Mississippi to challenge the legitimacy of the regular Mississippi Democratic Party, which allowed participation only by whites, when African Americans made up 40 % of the state population.

Answer this question: why did the mississippi freedom democratic party emerge at the democratic party convention in 1964?
To answer the above question, the relevant sentence is: It was organized by African Americans and whites from Mississippi to challenge the legitimacy of the regular Mississippi Democratic Party, which allowed participation only by whites, when African Americans made up 40 % of the state population.
Therefore, the answer is to challenge the legitimacy of the regular Mississippi Democratic Party , which allowed participation only by whites , when African Americans made up 40 % of the state population.