In Ultimate Comics: The Ultimates#16, Steve Rogers AKA Captain America is sworn in as President of the United States. He wins in a landslide without even trying, literally. Cap is elected as a write-in candidate when the country brakes out in civil war.
President Rogers doesn’t waste any bringing the country together. He ends a war between North and South Carolina by telling their leaders to shake hands or else.
But not everyone supports the President’s cowboy diplomacy. There are politicians beholden to special interest groups like supervillains, just like in the real world. Fortunately, Captain America also has some powerful allies.