The results of yesterday's local elections are still becoming clear, but one thing is obvious: Nick Clegg's party faces a humiliating defeat. The Liberal Democrats lost control of Hull, while ten out of 12 Lib Dem councillors in Liverpool lost their seat, and every single Lib Dem standing in Manchester was voted out.

The party also had to absorb a crushing double-digit loss in Sheffield, where Clegg has his consituency. By 6am in Scotland, it looked as though the Lib Dems were on course for just 15 per cent of the vote – the worst result of any third party in 50 years.

To make matters worse, it appears that the Conservatives are largely holding up their share of the vote while voters seeking to punish the government for its programme of spending cuts take it all out on the junior coalition partner.

With another resounding defeat expected this evening, when the results of the AV referendum come out, several senior Lib Dems have spoken out about the need to rebalance their role in the coalition after this bruising defeat and the dirty tricks used in the AV campaign.

Paddy Ashdown, a close ally of Clegg's and a supporter of the coalition, lashed out about Cameron's behaviour in the AV campaign and the impact that this will have on coalition relations.

The bottom line is that Liberal Democrats are exceedingly angry. We believe there has been a breach of faith here. If the Conservative Party funds to the level of 99 per cent a campaign whose central theme is to denigrate and destroy our leader, there are consequences for that.

What that means is that this is a relationship that is much less about congeniality; it becomes a business relationship, a transactional relationship, and maybe it will be all the better for that.

David Cameron is the Prime Minister. He sets the tone of politics in this country. It is an unhappy fact that when he was asked to dissociate himself from a campaign that was run on the basis of personalisation and personal attacks, and messages that were far more than some subtle bending of the truth, he refused to do that.

I have to say that he did not dissociate himself from a campaign whose nature I believe every previous British prime minister in my time would have disassociated himself from. That is a grave disappointment. This is a triumph for the regiment of lies. We live with pretty strenuous political campaigns in Britain, but these were downright lies.

So far the coalition has been lubricated by a large element of goodwill and trust. It is not any longer. The consequence is that when it comes to the bonhomie of the Downing Street Rose Garden, that has gone. It will never again be "glad confident morning".

Lord Oakeshott, the party's former Treasury spokesman in the Lords, agreed with this assessment of the Prime Minister's behaviour:

Cameron's performance in pretending he had nothing to do with the No campaign's attacks on Clegg was shameless. At least Pontius Pilate had the decency to wash his hands.

Simon Hughes, the deputy leader of the party, said that the Conservative-funded No camp had run a "fundamentally fallacious campaign that will reduce trust between the Tories and [my] party", adding:

From now on, we are very clear that we will keep to what the coalition has agreed in the coalition agreement. Other stuff will not be allowed in as policy unless our party has agreed to it.

The former Lib Dem MP Evan Harris added his voice to those calling for a refiguring of the so-far close coalition relationship:

We are going to have to make sure we recognise that there are some lessons to be learnt. We do not need to be so collegiate as we have been over the last year.

Others offered a more specific idea of the form that this rebalanced relationship might take – and the tools the party could use to ensure its interests are represented by the leadership. Mike Hancock, the vociferous Lib Dem MP for Portsmouth South, told the BBC:

He still needs our votes to get a majority in parliament. We have got to say that the price of our support is a bit harder than it has been up to now. Maybe he has had too easy a ride . . . Maybe we have to twist his arm a bit harder.

Although a loss on AV seems almost certain, Paul Tyler, Lib Dem spokesman on constitutional affairs in the House of Lords, indicated that the party still has some ammunition left – the redrawn consituency boundaries that the Tories are pursuing. He told the Independent:

Lib Dem MPs and peers don't hold the same view of our coalition allies as we did a few weeks ago. The No campaign has been funded, organised and in effect driven by the Conservative Party. It's a fact of life that there is less enthusiasm today than there was a month ago for the detailed day-to-day support for each other's priorities. It is by no means a done deal that the next election will be fought under new boundaries.

One thing is clear, then: the party is angry. While no one has presented a formal challenge to Clegg's leadership, nor has any senior figure rushed to defend him or the coalition. Although the more outspoken attacks have focused on Cameron's behaviour in the AV campaign, the subtext is clear: Clegg's chummy relationship with the Tories has translated into a battering at the ballot box and it must end.

If the party holds good on its promise to pressurise its leader into asserting its interests and identity more clearly, the next chapter of the coalition will be even more difficult for Clegg to navigate.