President Joe Biden made a surprise call to the MSNBC show Morning Joe to defend his position as the presumptive Democratic nominee and to slam the opponent he chided for telling lies and playing golf. “He’s just a liar!” Biden told MSNBC. “And he hasn’t done a damned thing since the debate. He’s been riding around the golf cart for 10 days, down in Mar-a-Lago.” Biden made his appearance just as his team released a defiant letter promising to pursue his presidential campaign despite calls that he step aside. Want more breaking political news? Click for the latest headlines at Raw Story. ALSO R…