"How he doesn’t get President Obama to endorse him — there has to be some reason why he’s not endorsing him," Trump said outside the Oval Office. "He was the vice president. They seem to have gotten along. And how President Obama's not endorsing him is rather a big secret," Trump mused, adding, "Then he goes and lies and said, 'I asked the president not to endorse me.' Give me a break."
Trump argued Biden made the assertion because "he’s embarrassed by the fact that Obama’s not endorsing him, so he goes out and says, 'I asked President Obama not to endorse me.' ... So it could be that President Obama knows something, but there is something going on in that brain of his."
Pressed on what exactly is going on in Biden’s brain, Trump said, "I think he’s off. He’s different. We’ve all known him a long time. I’ve seen him for a long time. Frankly, he looks different, he sounds different, and he thinks different. Other than that, I hope he does very well."
Trump in a recent interview with "Fox & Friends" declined to endorse his own vice president, Mike Pence, ahead of a possible run for president in 2024. Asked about his comments by NBC News's Chuck Todd, Trump said he didn't answer because it was a "surprise question."