Article continues below advertisementDonald Trump made it clear that Joe Biden is still very much on his mind.Trump, 79, took another swipe at his former political rival, 83, while speaking at the Detroit Economic Club in Michigan on Tuesday, January 13, talking about his speaking style and off-script remarks.Article continues below advertisement"You know, when you go up here, you take a big chance," Trump told the crowd. "Especially me because I go off teleprompter about 80 percent of the time.