What is the main job a president of US?

The main goal of a president varies with the times and the president. Sometimes there is a specific problem facing the nation and the candidates differ in their proposed solution. The winner usually tries very hard to get his solution passed by Congress and put into place. Some typical problems in the past have been a war or the eminent threat of war, the need to establish or abolish protective tariffs, whether the value of money should be based on gold or silver prices, government regulation of business, taxation in general, government stimulation of the economy , government control of health care and medical insurance , the increasing size of federal government and whether to increase of decrease military spending. Recent presidents have a major goal of being re-elected. I assume they all want to leave the nation better off than it was when they took office and to leave a favorable record in history.