ATLANTA — President Joe Biden was supposed to put the nation’s mind at ease over his physical and mental capacity with his debate showing Thursday night. 

But from the onset of the debate, the 81-year-old seemingly struggled even to talk, mostly summoning a weak, raspy voice. In the opening minutes, the president repeatedly tripped over his words, misspoke and lost his train of thought.  

In one of the most notable moments, Biden ended a rambling statement that lacked focus by saying,…