Israel's political world has been shaken by defence minister Ehud Barak suddenly quitting just weeks ahead of a general election.
Mr Barak, a decorated ex-general and former prime minister, said he would stay on in his post until a new government is formed following the January 22 vote.
"I didn't make this decision without hesitating, but I made it wholeheartedly," he told a hastily arranged news conference, saying he had been wrestling with the decision for weeks.
Mr Barak's resignation could mean the departure of the most moderating influence on hawkish Prime Minister Benjamin Netanyahu, who is expected to retain his job after the election. Mr Barak, who heads a small centrist faction in parliament, had often served as Mr Netanyahu's unofficial envoy to Washington in order to smooth over differences with the White House.
Mr Barak, 70, made the surprise announcement even after polls showed his breakaway Independence Party gaining momentum after Israel's recent military offensive in the Gaza Strip.
"I feel I have exhausted my political activity, which had never been an object of desire for me. There are many ways for me to serve the country, not just through politics," he said, adding his decision was spurred in part by his desire to spend more time with his family.
Mr Barak and Mr Netanyahu, who enjoyed a close working relationship for most of the past four years, reportedly have fallen out over whether to defer to the US on any attack against Iranian nuclear facilities.
Mr Barak's detractors in Netanyahu's Likud Party wanted him replaced.
Mr Barak evaded repeated questions about whether he might agree to serve as a cabinet minister in any forthcoming government, leaving open the possibility that he might still retain an impact on Israeli politics. While most cabinet ministers also hold parliamentary seats, small numbers have been appointed as "professional" ministers without being elected.