Isaac Herzog, who was elected head of the Labor Party in November, said that his ultimate goal is to replace Netanyahu. But he said he would back the prime minister if he genuinely pursues peace with the Palestinians and offered a political "safety net" should Netanyahu's right-leaning coalition rebel in case of substantial progress in recently restarted peace talks.
- Labor leader: Netanyahu is 'visionless CEO'
- Netanyahu an enigma, opposition leader says
- New Labor leader Herzog dreams of center-left bloc
As opposition leader, Herzog meets privately at least once a month with Netanyahu. Asked about the talks, Herzog said he has found a leader who "understands the real risks" Israel faces without a peace deal. At the same time, he said wasn't sure Netanyahu "has the guts to do it."
"I am not sure that he has the political ability or that he feels he has the political ability," he told a group of foreign journalists. "I am trying to encourage him to be bold enough to take those steps." He declined to discuss specifics, saying the talks are private.
Under heavy American pressure, Israelis and Palestinians began talks last year July after years of stalemate. So far, there has been no outside sign of progress and the talks have been characterized by mutual mud-slinging. The sides have set an April target date for a "framework" agreement.
The Palestinians seek the West Bank, east Jerusalem and Gaza Strip, territories captured by Israel in 1967, for an independent state.
While Netanyahu has reversed his long-standing objection to such a state, he remains opposed to many of the Palestinian parameters. Netanyahu wants to keep parts of the West Bank and says he will not share control of east Jerusalem, home to sensitive Muslim, Jewish and Christian religious sites.
Precondition: Jewish homeland
He also has insisted that the Palestinians recognize Israel as the Jewish homeland, a condition they say would undermine the rights of Palestinian refugees and Israel's own Arab minority.
The Palestinians have generally accused him of stalling and negotiating in bad faith, citing continued Israeli settlement construction in the West Bank and east Jerusalem.
On Tuesday, the anti-settlement Peace Now group said Israel had advanced preliminary plans to build 381 new homes in Givat Zeev, a settlement just outside of Jerusalem. Israeli defense officials involved in the decision did not immediately return a message seeking comment.
More than 500,000 Israelis live in the West Bank and east Jerusalem. The Palestinians and most of the West consider them to be illegal and an obstacle to peace, and US Secretary of State John Kerry has said the construction raises questions about Israel's seriousness.
Herzog said settlement construction "undermines" peace efforts and creates unnecessary friction. Even so, he said there was a "unique" and "golden opportunity" to reach peace at this time.
Herzog's Labor Party controls 15 of the 120 parliament seats -- making it the largest of the 12 parties in parliament that have not joined Netanyahu's coalition. He vowed his party would stand by Netanyahu at a time when members of his own nationalist Likud party have tried to shackle the prime minister's efforts.
"However, if we will be unfortunate and there will be no progress, I definitely see that we will replace the government and quicker than people project," he said. "He (Netanyahu) has to decide if he is a leader or a politician."