David Cameron and Nick Clegg insisted the coalition would survive the electoral reform referendum today despite increasingly bitter exchanges.
As the campaign entered its final stages, the Liberal Democrat leader renewed his criticism of the No camp for spreading "misinformation" about the Alternative Vote (AV).
Mr Clegg also said the issue was "far more important" than his own personal popularity or even the performance of the Government.
For his part, the Prime Minister warned that switching systems would be "expensive" and a "huge mistake".
However, both men stressed that the alliance between the Tories and Lib Dems would survive until 2015 regardless of the outcome on Thursday.
With polls suggesting AV will be resoundingly rejected, Labour leader Ed Miliband has complained that Mr Clegg's involvement has proved a "massive hindrance" to the Yes campaign.
Speaking on the BBC's Andrew Marr show, the Deputy Prime Minister conceded it was proving difficult to persuade people to "move with the times".
But he said it was too early to start a "post-mortem" of the campaign, adding that the royal wedding had been taking much of the public's attention.
"It is sometimes quite challenging to persuade people that we need to change things, move with the times," he said. "A lot of people probably haven't quite focused on it yet. I think there is a lot to play for between now and Thursday."
Challenged on whether his personal standing was harming the chances of a Yes victory, Mr Clegg replied: "It is far more important than any of us. It is far more important than the coalition government."
Despite previously condemning a "right-wing clique" behind the No campaign, the Liberal Democrat leader said he did not want to "personalise" the issue.
But he accused opponents of trying to "sow confusion". "Those who want to argue against change will try to amplify the fears," he added.
Appearing on the same programme, Mr Cameron said the Government would keep working together constructively after the public delivered its verdict.
"We are doing that already," he said. "We had a very successful Cabinet meeting on Tuesday, we will be having another Cabinet meeting this Tuesday. The business of government goes on."
Mr Cameron went on: "We always knew that this would be a moment of difficulty for the coalition because we always knew that Conservatives and Liberal Democrats would be on opposing sides.
"But I think it is perfectly possible, indeed we will demonstrate that it is possible, to continue a strong and effective coalition Government in the national interest for five years."
He said both he and Mr Clegg agreed that "if we succeed as a coalition we will both succeed as individual parties".
The premier insisted AV would be a "huge mistake for the country, so I hope there will be a strong no vote".
He denied suggestions he had broken a deal with Mr Clegg not to take a high-profile role in the No campaign.
And Mr Cameron refused to back away from claims that AV would be more expensive to run than first past the post - despite the suggestion being furiously rejected by Lib Dems.
"Clearly there would be a cost if we move to a new system," he said. "If we move to a system with voting machines, as I think would be the case, that would be expensive."
He also signalled that a No vote could draw a line under the prospects of electoral reform for the foreseeable future.
"No parliament can bind its successor," Mr Cameron said.
"But I think the arguments will have been had out in public and I hope if the No campaign wins that will be a decisive one."
The comments came after Lib Dem Energy Secretary Chris Huhne used an article in the Observer to call for a "progressive majority" to mobilise against the Tories.
In a piece penned jointly with shadow business secretary John Denham and Green Party leader Caroline Lucas, Mr Huhne wrote: "Britain consistently votes as a centre-left country, and yet the Conservatives have dominated our politics for two thirds of the time since 1900.
"On only two occasions in that long century - 1900 and 1931 - have the Tories won a majority of the votes. No wonder David Cameron says the current system has 'served us well'."
He insisted that "fair votes matter". "They matter for the millions of voters who suffered the worst excesses of the Thatcher government despite more than 54% repeatedly voting against her," he added.
Mr Clegg also told the newspaper he made "no apologies" for hitting back against "yelling and screaming" from the No camp.
"I kept my silence for weeks and weeks and weeks of ludicrous bilge being put out there ... to dupe and scare the British people," he said.
Research by BPIX for the Mail on Sunday found 51% were opposed to the reform, compared with 33% who supported it.
Among those against AV, 32% preferred first past the post because it is simple, 30% because it led to strong governments and 23% because they did not want another coalition.
The Prime Minister's prominent role in the No campaign also appears to have played a crucial role.
One in four said they respected Mr Cameron's view on the issue, compared to just one in 20 who said the same about his Lib Dem deputy.
Interviewed in the Sunday Times, Mr Miliband said: "Cleggmania has turned to Cleggphobia" and the public felt fooled by his claim to be "new and different".
The Yes campaign, which he has strongly backed, had been "massively hindered" by Mr Clegg's insistence on taking a prominent role, according to the Labour leader.
Alongside the referendum, elections are also being held on Thursday in many councils across the country and for devolved administrations in Scotland and Wales.
It is believed to be the biggest mid-term voting test in the UK's history - with all parties bracing themselves for the public's assessment of their performance.
Overall, BPIX put Labour on 42%, the Conservatives on 37% and the Lib Dems on 9%. A YouGov poll for the Sunday Times had Labour on 41%, the Tories on 36% and the Lib Dems on 10%.
Mr Huhne complained that Mr Clegg had been treated "outrageously" by senior Tories - including Mr Cameron - who have warned that AV could result in more broken promises by politicians.
Mr Clegg had done the "right thing" in making compromises on issues such as tuition fees to form the coalition, and did not deserve such "personal attacks".
"For Conservative leaders to give Nick the sort of criticism they have given him as a result is simply outrageous," Mr Huhne told Sky News' Murnaghan programme.
The Cabinet minister dismissed as "nonsense" speculation that his trenchant language is part of manoeuvring for a future leadership bid.
"I would be the first person to defend Nick Clegg," he said. "He is an outstanding politician and he has done what we needed to do."
Mr Huhne upped his assault on the Tories by insisting the party had a track record of resisting reform.
"The Conservative Party has throughout history always opposed changes in the electoral system that gave more power to people," he said.
"Whether it was votes for every man, votes for women."
But despite the tensions, he said after the referendum there would still be a "businesslike relationship" between the coalition partners.
"We have a businesslike relationship," he said. We have a coalition programme that we will go on delivering."