On the US Map (not the map of the battle), press Start to go into the Options Menu, then get into the Cheat Menu, then enter X, B, B, X, B. This Code makes sure that your Political Reputation is raised by 1 towards the Green Level (Good Level). Note: You might have to enter this code more than once.

Political Reputation raised by 1 towards the Green Level - X, B, B, X, B