Presidential hopeful Kamala Harris was plagued by a splintered relationship with President Joe Biden, staffers who couldn’t stand her, unthinking insults about her fellow Americans, and diplomatic disasters during her time as vice president, Beltway insiders told RadarOnline.com. Yet despite her struggles with popularity as second-in-command, Harris, 59, was neck-and-neck with her rival, Donald Trump, in national polls as the country waited to hear Biden speak from the Oval Office for the first time since he dropped out of the race. Harris quickly accepted the nomination after Biden endorsed h…