By refusing to join the league of nations.
Because it got America over thousands of miles of land for a very cheap amount of currency.
The President, however, can influence and shape legislation by a threat of a veto. By threatening a veto, the President can persuade legislators to alter the content of the bill to be more acceptable to the President. Congress can override a veto by passing the act by a two-thirds vote in both the House and the Senate.
