Prime Minister Benjamin Netanyahu's governing coalition will survive the departure of the Kadima party but the premier has been weakened by the exit, Israeli observers said on Wednesday.

Netanyahu's "super-coalition" shrank on Tuesday, with the departure of the 28-seat Kadima, the parliament's largest faction, over the issue of national service for all Israelis.

Kadima's exit, which came just 70 days after its leader Shaul Mofaz took the party into a surprise coalition with Netanyahu, reduces the premier's hold from 94 to 66 MPs in the 120-seat Knesset, or parliament.

The largely rightwing coalition left behind depends on the support of the secular, ultra-nationalist Yisrael Beitenu party headed by Foreign Minister Avigdor Lieberman and its 15 seats.

And despite differences between Yisrael Beitenu and Netanyahu's rightwing Likud over the issue of conscription, Lieberman said he had no plans to leave the coalition for now.

"We won't leave the coalition. We are going to continue to fight from within the government," he told Israel's army radio.

Environment Minister Gilad Erdan, who is close to Netanyahu, ruled out an early election following Kadima's departure. Elections are currently scheduled for October 2013.

"There won't be elections tomorrow," he told army radio. "For more than three years, we managed without Kadima, and we intend to carry on."

But commentators said that while Netanyahu's government was likely to hold on until at least next year, the premier had been weakened by the speedy reversal of his decision in early May to bring Kadima into the coalition.

Observers said Netanyahu was now seen as having caved in to the demands of the ultra-Orthodox Jewish parties in his coalition, which oppose attempts to force religious Jews to complete military or community service.

And they warned that the premier appeared to have "sacrificed" his secular coalition partners, including Yisrael Beitenu and Kadima, which want to see ultra-Orthodox Jews and Arab Israelis participate in national service.

Recent polls show two thirds of Israelis -- who are required to complete three years of military service for men or two years for women -- agree that all sectors of Israeli society should be required to complete national service.

Ayala Hasson, a political commentator for public television, said Netanyahu had erred by bringing Kadima into the coalition earlier this year to head off early elections that he was expected to win with ease.

"By changing tactics, Netanyahu -- who would have been the winner -- made a mistake," she said.

But Nahum Barnea, writing in the top-selling Yediot Aharonot, said both Netanyahu and Kadima's Mofaz had failed to properly understand each other's motives.

"Netanyahu overestimated Mofaz's despair. He didn't understand that even a desperate politician can be ambitious," he wrote.

"Mofaz misunderstood Netanyahu's intentions. He thought that Netanyahu brought in Kadima in order to get things done. He did not realise that Netanyahu had brought in Kadima in order to not get things done."

Analyst Ben Caspit, writing in Maariv newspaper, warned that Netanyahu "needs to decide how to call early elections so as to minimise the damage."

"Time is working against him," he wrote. "Netanyahu is lucky that there aren't any serious adversaries visible on the horizon at this point, but that might change too."

Israeli army radio said it was possible that elections could be pulled forward by six months to April, but not due to the departure of Kadima or the dispute over universal conscription.

Any move to bring the vote forward would likely be a bid to avoid a voter backlash over the looming fiscal austerity measures that are expected to be imposed next year due to Israel's economic slowdown, the radio said.