A Russian parliamentary committee head has quit Prime Minister Vladimir Putin's United Russia party to join the opposition Communist Party, the KPRF. Sergei Shishkaryov, head of the Transport Committee in the Duma, is the latest of several lawmakers who have quit the ruling United Russia party ahead of parliamentary elections in December. "He [Shishkaryov] is joining the KPRF," communist lawmaker Igor Edel told RIA Novosti on Tuesday. Shishkaryov has had disagreements with the Transport Ministry and frequently criticized its policies, including plans to build toll roads. He was not available for comment. Earlier this month, Siberian deputy Alexei Lebed and southern Krasnodar region deputy Igor Isakov resigned from United Russia. Three months ago, Joaquim Crima, the first black man ever to stand for public office in Russia, quit Putin's party, claiming that it "acted as a brake on our country's road to democratization." The latest opinion polls suggest the party's approval rating has dipped below 50 percent for the first time since 2007. Putin has recently established a People's Front movement in a bid to attract electoral support for candidates not associated with United Russia.