Rome, July 16 - Lower House Speaker Laura Boldrini on Tuesday said Northern League bigwig Roberto Calderoli was guilty of "intolerable backwardness" for likening Italy's first black minister, Cecile Kyenge, to an orangutan. Calderoli and his party, which frequently adopts extreme stances on migration issues, have so far resisted calls for him to quit as deputy Senate speaker after a barrage of criticism for his comments directed at Integration Minister Kyenge at the weekend. "No one can remove him. It can only be his decision," said Boldrini, after League leader and Piedmont Governor Roberto Maroni rejected a call to intervene from Premier Enrico Letta. "The words of Deputy (Senate) Speaker Calderoli show intolerable backwardness. "People who hold institutional roles cannot say anything that crosses their minds. "They have to be up to the role. If he cannot control himself he is not capable of doing his job". Calderoli has said he will comment on the furore in the Upper House later on Tuesday.