A former adviser to Barack Obama struggled to contain his tears Sunday as he described his pain at President Joe Biden’s departure from the campaign trail. Van Jones — who has publicly called for Biden to step down over the past few weeks — repeatedly struggled to keep his voice from cracking as he spoke to CNN’s Kaitlan Collins. “Joe Biden’s body may not be as strong as it used to be, his language skills may not be as sharp as they used to be. But his heart is as big as ever. His heart is as big and as true and as strong, and this is the difference between a politician and a leader. Want more…