Members of Israel's Kadima party have thrown their weight behind Prime Minister Ehud Olmert after a key cabinet minister said he should resign.
Mr Olmert has vowed to stay in office and "fix" his mistakes
Kadima lawmakers met in special session after Foreign Minister Tzipi Livni called on Mr Olmert to quit over his handling of last year's Lebanon war.
The results of an inquiry into the government's handling of the conflict were highly critical of Mr Olmert.
Israel's parliament will debate the findings in a special session.
Mr Olmert has said he will not quit but will implement the changes recommended by the report.
After a six-month investigation led by retired judge Eliahu Winograd, Mr Olmert was accused of "serious failure in exercising judgement, responsibility and prudence".
The BBC's Tim Franks, in Jerusalem, says that for the time being the prime minister is fighting back.
However, despite a dearth of popular replacements within the coalition it is hard to see Mr Olmert surviving in the long term, he adds.
Recent opinion polls have suggested that a majority of Israelis want Mr Olmert to stand down.
And thousands of people are expected to express their dissatisfaction at a protest rally in Tel Aviv on Thursday night.
Mr Olmert addressed his 29-strong parliamentary bloc hours after Ms Livni held a news conference saying he should stand down.
"I am in a personally uncomfortable position, but I will not shirk my responsibility and will fix all the mistakes," Reuters news agency quoted Mr Olmert as saying.
After the meeting, Deputy Prime Minister Shimon Peres said Kadima had offered Mr Olmert "unprecedented support".
"It was a great day for Kadima, which came out unified and convinced of its strength," he said.
There was less unity earlier on Wednesday, when Ms Livni spoke to journalists after a head-to-head meeting with Mr Olmert.
She said she would not resign from the government or try to oust Mr Olmert herself, but would stand as a candidate to replace him.
Kadima should stay in government, she said, adding that Israel should not hold a snap election.
Ms Livni said she had told the prime minister that resignation "would be the right thing for him to do".
"It's not a personal matter between me and the prime minister - this issue is more important than both of us," she said.
"However, large-scale change is needed now."
Ms Livni, who was a founder member of Kadima when it was formed by former Prime Minister Ariel Sharon, also serves as deputy prime minister.
Defence Minister Amir Peretz and the former military Chief of Staff Dan Halutz were also heavily criticised by the report into the conduct of the 34-day conflict with Hezbollah.
The inquiry, commissioned by Mr Olmert, did not explicitly call for resignations