 On both occasions he withdrew his candidacy, the first time in favor of Leonid Kravchuk, and the second time in favor of Petro Symonenko.Tkachenko was a member of the Eleventh Convocation of the Parliament of the Ukrainian SSR, and since 1994 has been elected to the Parliament of Ukraine for four consecutive terms.Between May 1994 and April 1998 he was the First Deputy Chairman of the Parliament, and was Chairman of the Parliament from July 7, 1998, to January 21, 2000, when was dismissed for violating parliamentary session regulations.