Donald Trump has accused Joe Biden of “not knowing what he said” as the pair locked horns on the southern border crisis. The former president said he struggled to follow the comments being made by his successor. Joe Biden was accused of having a brain freeze by many social media users, and Trump appeared to lean into that. “I really don’t know what he said there at the end of that sentence”, said Trump. “I don’t think he knows what he said either.” Biden offered no response and instead glared back at his opponent appearing baffled by the remark. LATEST DEVELOPMENTS WATCH: ‘You have BETRAYED Br…