I also do not like the Nazi references. If anyone today in the U.S. is compared to the Nazis, it devalues the horror of the Nazis.
There really is a valid comparison today. It is the Islamofascists. Give them time and they are this century’s Nazis, or worse.
Though, if one considers the modern day left to be the butt boys and useful idiots of the Marxists, and if one counts up the murders committed by the Marxists, such as Stalin and Mao and Pol Pot, then one can make a good case that the Marxists and fellow travelers are far worse than the Nazi's and their close descendants, the Jihadists.
For a damning look into how the left serves as the useful idiots of the Marxists, do a YouTube search for Bezmenov. You will find several 5 or 10 minute snippets from an interview of a KGB agent who defected. For example, he explains how the leading voices of the Left be the first to be lined up and shot if the Marxists gain even brief control. He spells out how the lies, deceits, moral degeneration and social collapse caused by our modern leftists are the intentional first stage in destroying America.
For a damning look into the evils of the Chinese Communist Party, see the "Nine Commentaries on the Communist Party", either read aloud by a fine narrator with appropriate images found in a YouTube search for Nine Commentaries on the Communist Party, or in online text at The Epoch Times, or in book form at Amazon.com They make the case that the Chinese Communist Party (CCP) has been responsible for more "premature deaths" than all the other Communists, Nazis and Jihadists combined.
For a humorous, but deadly serious, look into the Mind of the Liberal, see Evan Sayet's speech to the Heritage Foundation How Modern Liberals Think, on YouTube.
And so that no one protests that I am not giving our Islamic Jihadist colleagues equal time, see perhaps the best exposition on the world war they are engaging against civilization, in six parts at YouTube again, as Obsession: Radical Islam's War Against the West