Ministers on Sunday voted 18-3 to reject a proposal to delay the withdrawal from Gaza and four West Bank settlements by six months.
The delay was proposed by Agriculture Minister Israel Katz, a hardliner opposed to the withdrawal. The cabinet vote means the forced evacuation of settlers in Gaza and four West Bank settlements will begin in mid-August, as planned.
The cabinet's wrangling over the Gaza pullout highlighted the bitter rivalry between Prime Minister Ariel Sharon and Finance Minister Benjamin Netanyahu, a former prime minister.
Netanyahu voted in favour of the delay, a direct challenge to Sharon.
Netanyahu also plans to be absent from a parliamentary vote on Wednesday on the same issue, and Sharon has threatened to fire him.
The sweeping victory for Sharon came after the premier told his ministers that he would not countenance any further delay.
"Any delay to the withdrawal would be dangerous and as a result must be ruled out," Sharon told the cabinet in comments broadcast by Israeli radio.
Earlier this year, Sharon pushed back the start date of disengagement by three weeks but he has since consistently ruled out any further delay, regarding such as calls as blatant attempts to block the entire project.
While support for the pullout had been slowly eroding in recent months, it bounced back last week after a spate of violent protests by opponents.
Finance Minister Benjamin
Netanyahu supports a delay
A poll published by the top-selling Yediot Aharonot newspaper on Friday said that 62% of respondents backed the withdrawal, while 31% were opposed. Yediot's last survey published on 10 June showed only 53% were in favour while 38% were against the plan.
Netanyahu hinted on Sunday that he would absent himself from the vote in parliament, and thus avoid the need to resign by breaking the tradition of collective responsibility.
"I will vote Sunday according to my conscience and I cannot vote on Wednesday against my conscience," he told reporters before the start of the cabinet meeting.
Opponents of disengagement are looking to Netanyahu to come off the fence and give some tail wind to what appears to be a doomed bid to halt the first ever Israeli withdrawal from occupied Palestinian territory.
Netanyahu last week said that the disengagement would have a sharply negative impact on the economy but said that he would not imperil his programme of economic reforms by quitting the cabinet.
The Yesha council, the main settlers' organisation, wrote to Netanyahu last week saying that it "is still not too late to stop this crime".
Netanyahu is aware that the Gaza pullout remains deeply unpopular in his and Sharon's right-wing Likud party and that a resignation from the government over the issue would put him in pole position to challenge the premier for the party leadership.
Trade Minister Ehud Olmert, Sharon's chief cabinet ally, accused Netanyahu, of "undermining the prime minister with his intriguing".
Deputy Prime Minister Shimon Peres, whose centre-left Labour party entered the coalition back in January specifically to guarantee that the Gaza pullout does take place, said that any delay would be intolerable.
"We will not accept the slightest delay and would not leave the government in such a situation," he said.