The president has many jobs, for instance the president is the chief of state, this means that he is in charge of inspiring all Americans.  Second the president is the highest boss of all other government workers.  This means he can tell anyone in the government what to do and when to do it.  (Including the Military)  He is also in charge of telling the American ambassadors what to say to all the foreign governments.  The president can also influence the law making process of the congress.  The president is also the chief of party. With this power he can help people of his own party to be elected into office.  Lastly the president is in charge of the economic status of the United States. 

http://www2.scholastic.com/browse/article.jsp?id=4683