I don't personally believe this, but OTOH Obama has never botherered to provide the documentation showing otherwise.
a Marxist
he certainly has many goals in common with Marx.
a Nazi
Calling him "a Nazi" is over the top, but there are undeniable similarities in style and goals.
a racist
This one is indisputable IMO, as shown by his automatic assumption that the cops were to blame in a case of which he admitted he knew nothing.
intent on interning the elderly and euthanising the disabled
Only the ding-dongs have made such claims. What many have said is that this will be the effect of his policies, not that it is his intent.
He HAS expressed that as his intent. Remember the "blue pill" comment? Have you read "The Plan", which he is plainly following? Oh sure he hasn't put it that crassly, but his axiom is clear: if your life "isn't worth living" by his standards, you shouldn't ... he may not off you, but he'll persuasively & rhetorically say "are you sure it's all worth it?" and hand you the forms directing the doc to pull the plug.
If it were not his intent, he would not advocate policies promoting the consequences.