What challenge do presidents in particular face when persuading an audience?

The answer is "they must appeal to several different groups. "

The President of the United States is the head of state and head of legislature of the United States of America. The president coordinates the official part of the national government and is the president of the United States Armed Forces.  

Presidents confront challenges ordinary and are examined for each choice they make. They should be a pioneer and show certainty for the general population. They need to settle on choices that can influence a huge number of individuals.

the values of the selma marchers was to bring   their ability to vote into law. mlk was not hat march, which was protesting toward lbj