The electoral oblivion apparently confronting the Liberal Democrats as led by Nick Clegg was underscored on Monday by leaked opinion polls in four seats showing that the party will be wiped out.

Commissioned by a Lib Dem supporter from ICM and subsequently passed to the Guardian, the polling indicates that the Lib Dem leader would forfeit his own Sheffield Hallam constituency at the next election.

The party would also lose its seats in Cambridge, Redcar and Wells, costing MPs Julian Huppert, Ian Swales and Tessa Munt Westminster seats.

If the business secretary, Vince Cable, were to take over as leader, the Lib Dems would perform marginally better, the data suggests. Appointing Danny Alexander, the chief secretary to the Treasury, would give the party a more modest boost.

The damning verdict comes after a crestfallen and visibly exhausted Clegg said in the early afternoon that he would not buckle in the face of woeful European election results which cost the party 10 of its 11 MEPs and left it in fifth place.

Ukip topped the polls – winning 23 MEPs – leaving huge questions for all three mainstream parties, but especially for Clegg's strategy of confronting the Ukip leader, Nigel Farage, in two TV debates that he was deemed to have lost.

Facing calls to quit from some party activists and parliamentary candidates, Clegg claimed it had not "crossed his mind" to resign, adding that he would not hesitate if he thought it would help the Lib Dems in the long term.

"If I thought any of our real dilemmas would be addressed by changing leadership, changing strategy, changing approaches, bailing out now, changing direction, then I wouldn't hesitate advocating it," he said in a carefully choreographed interview.

Clegg's supporters insist no purpose would be served by swapping leader less than a year before the general election .

But the polls counter the claim that the party would do no better if Clegg stepped aside.

They will also darken the already distraught mood in the party by challenging the argument that personally popular incumbent Lib Dem MPs have enough local support to resist the current wave of national antipathy towards the party. Many of the party's 57 MPs have comforted themselves that they can resist the national mood.

The polls show that if Clegg remains leader he would lose in Sheffield Hallam to Labour by 33 points to 23. He would even come behind the Conservatives. In the 2010 election, Clegg obtained 53% of the popular vote.

Huppert would lose Cambridge to Labour by 41 points to 28. In Redcar support for Swales collapses into third place on 16 points behind Labour (46) and Ukip (20). Munt, MP in Wells, Somerset, would also lose to the Conservatives by a massive 41 points to 21.

A Cable leadership would reduce the Labour lead in Cambridge by 12 points, in Redcar by four points, in Sheffield Hallam by eight points and in Wells by seven points to the Tories.

In both Cambridge and Hallam, a Cable-led Liberal Democrat party would be competitive with Labour, but if he were leader the party would still be left trailing in Redcar and Wells.

Alexander would have a positive impact in each seat, but not as large as Cable's. On average the Cable effect in the four seats is +8 and the Alexander effect +5.

The polls undertaken in April and May are of all respondents expressing an intention to vote and are turnout weighted. They do not include some adjustments ICM uses for national polls. The polls also question the value of a personal-vote showing. Although Munt, Swales and Huppert have positive ratings for a good job by their constituents, fewer than half recognise them.

Any momentum to remove Clegg had appeared to dissipate on Monday and the leak of the polls is clearly designed to persuade Liberal Democrat MPs to sense how perilous their chances of survival are with Clegg at the helm, as well as the possibility that Cable or Alexander as leader gives them better prospects.

Cable, on a trade delegation in China, issued a statement saying there was no leadership issue, adding that Clegg personally deserves "tremendous credit for doing the bold thing in standing up to the Eurosceptic wave which has engulfed much of continental Europe".

He added: "We have also undoubtedly taken a kicking for being in government with the Conservatives and having to take some extremely tough decisions in the national interest. But now is not the time for infighting and introspection. The party must hold its nerve."

Clegg in his one broadcast appearance – a pooled interview conducted by a BBC journalist – admitted he had not realised how unpopular forming a coalition government would become, but said: "Just at the point when our decisions, our big judgments are being vindicated, we are not going to buckle, we are not going to lose our nerve and we are not going to walk away."

The deputy prime minister said he accepted that many people had serious questions about his leadership. "I don't begrudge any individual for raising searching questions, asking challenging questions about strategy and about leadership. It is the most natural thing in the world after the electoral losses of the last few very, very difficult days."

In a sign that unease is spreading to normally loyal MPs, Sir Nick Harvey, who was sacked as a defence minister in a reshuffle in 2012, called on the Lib Dems to put more distance between the party and the Tories. Harvey told The World at One on BBC Radio 4: "There is a perception on the part of voters that we have got ourselves too embroiled with the Conservatives."

A Liberal Democrat spokesman said: "We have no idea where this polling comes from but it has clearly been commissioned and leaked for political purposes. It bears no relation to the result we saw on Thursday night, where Liberal Democrats secured 38.7% of the vote across Sheffield Hallam. Labour managed 23.6%, whilst the Tories came fifth with just 10.7%."