Frank Luntz and Radek Sikorski have claimed Johnson touted himself as a supporter of the Social Democratic Party , then a dominant current at the university , as a strategy to win the Union presidency , though Johnson denies he was more than the SDP 's preferred candidate . Frank Luntz and RadosÅ aw Sikorski have claimed Johnson touted himself as a supporter of the Social Democratic Party , then a dominant faction in the university , as a strategy to win the Union presidency , although Johnson denies that he was more than the SDP 's preferred candidate .