Ehud Olmert is battling to keep together Israel’s fractious multi-party government, amid rising tensions between the prime minister and his rightwing coalition partner over the current Middle East peace talks.

Mr Olmert is due to meet the leader of the Yisrael Beiteinu party on Tuesday in a bid to maintain the backing of Avigdor Lieberman and his 10 fellow parliament members. The meeting was triggered by Mr Lieberman’s opposition to the opening of talks on the core issues of an Israeli-Palestinian peace agreement, such as the status of Jerusalem and the final borders of a Palestinian state.

Mr Lieberman, who has said in the past that such a move would cross a “red line” for his party, will announce a decision on whether to pull out of the government or not on Wednesday, his spokeswoman said. She added the party was also opposed to evacuating Jewish settlement outposts in the Palestinian West Bank, which have been erected without the backing of the government.

“The prime minister wants to keep the coalition strong and he doesn’t want to see any of his coalition partners depart. Israel needs a strong government and political stability,” Mr Olmert’s spokesman said on Monday.

The latest tension underlines the chronic vulnerability of Mr Olmert’s fractious government, which now faces erosion from both left and right: the centre-left Labor party, which forms the second-biggest bloc in the coalition, is also debating quitting the government.

Mr Olmert has proved a master of political survival since he took office two years ago, repeatedly shrugging off coalition crises and calls to step down, including those from within his own party. The prime minister, who commands 78 out of 120 seats in the Knesset, is also in a position to replenish the ranks of his coalition by bringing in other small parties, should Yisrael Beiteinu quit.

But the rising discontent within his government – coupled with Mr Olmert’s low standing in the opinion polls – is likely to make it even harder for the prime minister to forge a peace agreement with the Palestinian leadership. Mr Olmert and Mahmoud Abbas, the president of the Palestinian Authority, are committed to reaching a peace deal by the end of the year, but face an uphill struggle to overcome opposition from hardliners who oppose concessions over the three core issues – borders, Jerusalem and where to settle Palestinian refugees.

Yet the biggest domestic test for Mr Olmert is likely to come later this month, when the Winograd committee publishes its findings into the government’s handling of last year’s botched war in Lebanon.

With the report expected to contain harsh criticism of Mr Olmert’s leadership during the conflict, Labor leaders will face intense pressure from the opposition and from the party’s rank-and-file to withdraw their support for the prime minister.

According to an opinion poll published in Haaretz newspaper last week, the rightwing Likud opposition party would win 34 seats in the Knesset if an election were held now. Mr Olmert’s Kadima party would slump from 29 to 13 seats while Labor would win 17 seats, down from its current 19.