Elkin began by lamenting his resignation, which he said had been a difficult decision to make. "Like you, I believe that 'a political party is not a soccer team', and that each public figure must ask himself whether he truly believes in the flag under which he attempts to earn public trust," he wrote.
Elkin said he had been disappointed in the party's conduct ever since the Annapolis Peace Summit and "the excessive promises made to the Syrian president." He said these, among other things, had marked Kadima's steady progress towards the left wing.
He said the party was now located somewhere between Meretz and Labor, and enthusiastically promoting "radical leftist ideas such as the Geneva Initiative". He said he could no longer be part of a party whose leader has become "an outstanding representative of the Left."
Sources affiliated with Livni had no lamentations on hand for Elkin's abrupt departure. "Good riddance," said one. He said the MK had been "working against Kadima from day one", and that he had attempted to thwart Shimon Peres' election to the presidency.
Elkin, 37, made aliyah from the former Soviet Union at age 19. He was elected to the Knesset during the most recent vote, and has participated in various committees. In recent party primaries he voted for Transportation Minister Shaul Mofaz, who ran against Livni.
Attila Somfalvi contributed to this report