In this world, Adolf Hitler never invaded Poland, and so WW-II never happened. The Japanese never attacked Pearl Harbor, so America never goes to war, so there was not any nuclear bomb. Berlin was never taken by the Soviets, so there is no cold war.
The National Socialist Party of America appeared in late '86 as a revolutionary party that participated during the 1987 presidential race after Ronald Reagan quit. He suffered from Alzheimer's.
Most of the citizens thought that if the Nazi won the presidential election, it would become just like Germany with total military control and punishment to the non-Nazi followers. The Jewish population fear that the atrocities that were rumored to be happening in Germany against them could be real and happen to them.
All this ends when the National Socialist Party of America was expelled from the presidential elections and stops been recognized as a political party. Its leader, Antonio Gustav, an American with German parents, made a call to their followers to manifest on every city's streets. Soon, the manifestation turned deadly when five Nazi partisans entered the capital with rifles and grenades, killing 43 people. This was repeated in different cities including American army bases.
The manifest against the government turns into a battle for the control of the U.S.
Germany threatened America to launch an attack against them if they do not recognize the National Socialist Party of America as a political party and let them participate on 1987 presidential elections.