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 language of nature was a manifestation from god as he said "let there be light" and there was light the world began to assume visible, comprehensible form.

what ever we know now think of the old vision of creation we can be sure that with out the speaking of word -without language- we would have no science today with its striking power to illuminate the world.

answer; all over the above; //everybody