Slomiansky headed the parliamentary lobby for elderly persons during the Sixteenth Knesset. Since 2003, he is serving as the party's group chairperson at the Knesset, holding this position during the party's split on the background of the disengagement plan. For the 2009 elections, he won a fourth place on the Jewish Home list, but lost his seat when the party won only three seats. In the 2013 election, he was placed third on the Jewish Home list and was re-elected to Knesset. In 2011, he was appointed Vice President of the Lander Institute, replacing Reserves General Y. Amidror, who was appointed to the Chief of Staff of the National Security Institute.