In the manner of lacing well water with poison, the Republican right has sought to use patriotism as a deadly sword against progressive Democrats.

The propaganda maneuver is based on a simple principle.  Only the Republican right can define patriotism.  As a result, the most reactionary Republicans engaging in the most odious conduct, including unconstitutional acts of war and corruption, are deemed patriotic.  

Those attacking such individuals and their actions are ipso facto deemed unpatriotic and of engaging in conduct that "gives aid and comfort to the enemy."

Many cite the mid-twentieth century conduct of Richard Nixon and Joseph McCarthy as the opening salvo in the strategy to paint progressives unpatriotic, but the effort was launched when President Franklin Delano Roosevelt developed a coalition of union and middle class support based on strong federal action to counteract the tragedy and suffering incurred during the Great Depression.