The left has an affinity towards zombies as they are have so much in common. Both no longer have upper mental functions. They, like the zombies, operate from the Id portion of the brain -- the old lizard brain that acts upon instinct alone, plus a few have some cortex memory. The smarter zombies pound glass panes with a rock, instead of their bare fists.
Both, from instinct, have a need to feed. Both, must feel on others, as they have lost the ability to product their own food, or work for it. For a zombie, the feeding does no good as their digestive tract, like the rest of them is rotting and not functioning. Progressives can still digest what they feed upon, but it just increases their desire to seek out more from the remaining productive and rational portion of the human race.
Neither, will ever produce something of lasting value, or, indeed, of any value. Witness the slow collapse of Europe, in general, and much of South America.
In short, the best strategy is to avoid both. However, remember if you must -- head shots thru the open mouth (teeth cause ricochets) to separate the spinal cord from the Id is the best solution. Or, in desperation, decapitation, when close up. In either case, close up, their breath will probably be atrocious.