Links between a Republican and a Nazi.
The Nazi movement, made famous by Adolf Hitler in the late 1920's and 1930's, strived to create a master race that would dominate Europe. As a result of several events, World War II was fought between the Axis and the Allies.
Note: not to be confused with 'Axis of Evil'

The republican political movement in America also strives to create a 'master race' of white supremacists, and therefore draws a unique parallel with the Nazi movement in the 1930's.

Similarly, the economic policies of the two regimes are strikingly similar, with both leaders (George W. Bush and Adolf Hitler) both believing in spending money over fiscal responsibility (often to distract citizens from other events). Evidence of this can be seen in the CIA world factbook - which puts the US as the 39th most debt ridden country (in terms of GDP as a % of public debt). Although this may not sound amazing, this puts countries such as Mexico, Libya, Iran, China, Zimbabwe and Russia all with lower levels of public debt than America.
In Nazi Germany before WWII, there were also high levels of public debt, which many historians will argue was the cause for the invasion of the Low Countries after the conflict started. In America today, wars against less developed countries are also being used for financial gain, e.g.: the Iraq war.

Both believe in the right of a citizen to posess a firearm and to sacrifice certain freedoms for the benefit of the state. This overriding belief in the supremacy of one individual above another (could also be the belief in one nation over another) is called racism and can be seen openly in both republican politicians and in the former Nazi regime. A good example of this would be the lack of black or hispanic presidents in America, even though the latter comprise almost 40% of the male population.

1. An insult used by those opposed to the United States's Republican Party suggesting a similarity between it and Adolf Hitler's National Socialist (Nazi) Party.

The word suggests that the target of the insult is representative of the supposedly fascist goals that the insulter believes the two share.

2. If the link between the parties does not apply to the target of the insult or the insulter does not understand the link implied by the origin of the term, then Republicanazi can simply be used as a generic insult for a Republican.