The recent George Soros-backed takeover of 18 Hispanic radio stations, including Miami’s flagship conservative Radio Mambí, is doomed to fail, according to two hosts who quit the station as a result of the planned new progressive agenda. “This is going to be a failure — I am 100 percent sure of that,” Venezuelan-born former Radio Mambí host Lourdes Ubieta told The Post she believes. She quit the station after she learned of the takeover during the summer. “They did this to silence conservative Hispanic voices but it’s not going to work.”