This is an excellent article by actor Michael Knowles about 
why Democrats call us Nazis:
The answer lies in the intellectual heterogeneity, or lack thereof, 
within the two major parties. Since the Reagan Revolution, the 
Republican Party has counted in its ranks at least four distinct 
political groups: traditionalists, neoconservatives, libertarians, and 
the religious right. In his excellent piece “Four Heads and One Heart,” 
political scientist James Ceaser observes that these four major factions
 of the Republican Party often approach politics from fundamentally 
different points of view. In order for libertarians to share a “big 
tent” with the religious right, they must force themselves to consider 
an opposing point of view, understand the merits of its arguments, make 
ideological concessions, and compromise. 
The Democratic Party has no such philosophical disagreements and 
therefore no such reason to compromise, at least in the years since 
Howard Dean, Nancy Pelosi, and Barack Obama brought the party back from 
the brink of practicality. Conservative “Blue Dog Democrats” and 
Clintonian “New Democrats” have almost entirely abandoned ship: all that
 remain are ideologically pure progressives. Devoid of any internal 
challenges to their ideas, the so-called progressives are left in a 
Democratic echo chamber, finally free to, well, progress.
 Read the whole thing.