As Britain fumbles its way towards the exit door from the EU, any optimism about leaving has disappeared for many core voters. Prior to the referendum and then for the six months that followed, Leave voters consistently told us in our research that life after Brexit would be fantastic – perhaps best summarised by what one Leave voter told me in March 2017: “I am looking forward to it. This is a fantastic opportunity to rebuild the country: more police, better hospitals, more schools and teachers.” In their eyes Britain, for so long shackled by the EU, would emerge into a brighter and better future.

But now that conviction about the sunny uplands of a post-Brexit UK has gone. Leave voters come across as crestfallen, angry and disconsolate about Brexit. Their positions on what should happen next vary – from saying that we should leave without a deal to having changed their mind and wishing we could stay – but what is consistent is their lack of enthusiasm.

Indeed, many think that we are failing to deal with other key issues as a result – 73% of the public agree that the UK’s focus on Brexit has significantly hampered our ability to deal with other major issues facing the country. For those who still want to leave, the reasons for leaving are less and less about what we might achieve – although for die-hard Leave voters the twin pulls of sovereignty and immigration remain strong – and more about a point of principle. The country voted to leave, and that vote should be honoured.

The body language in Slough last week spoke for itself – initially cheery demeanours switched to slumped shoulders, resigned facial expressions and sighs of exasperation once the conversation moved on to Brexit. Neither Leave nor Remain voters now think that the Brexit we are heading for is a good idea in itself: “We’ve not got anything back, we’ve given loads of concessions, they’re in control.”

Leave and Remain voters and also united in their despair at the political classes. I have run countless focus groups on Brexit over the last two years, but rarely have I seen any more dejected citizens than last week in Slough. There is of course criticism of Theresa May, Jeremy Corbyn and other individuals, but above all the message is that the whole political establishment has failed the public. 83% of the public agree that ‘the entire political establishment has failed the country on Brexit’. Voters bemoan a perceived lack of decisiveness: “Just make a decision – leave or don’t leave.” But perhaps more than anything they despise the descent into ‘party politicking’ which they feel have characterised the last few months. “They’re not interested in the general public, they just want to keep their party in.”

This is particularly dangerous for Jeremy Corbyn. Previously his profile among the general public has been that he is “a man of principle” who tells it how it is. Even his many detractors respect what they see as deeply held convictions and his willingness to act upon these.

But over the last few weeks, it looks to the public as though Corbyn has strayed from this. His apparent unwillingness to say what he wants from Brexit, his seemingly tangential determination for a General Election (“A General Election – what would that do?”) and his lack of decisive action on Brexit all speak to a man driven by party political tactics rather than the national interest (or even the interests of those he seeks to represent).

Some 69% of the public agree that Corbyn is more concerned about party politics than the national interest. Just 16% disagree (the comparable figures for Theresa May are 45% and 39%, suggesting a much more divided take on her performance). Time will tell whether this amounts to a mortal blow to his public image – in a BritainThinks poll over the weekend, three in five members of the public said that their impressions of Jeremy Corbyn had got worse since the referendum (just 10% said they had improved).

As for Theresa May? Voters respect her commitment to her cause in the face of adversity, but their respect doesn’t stretch any further than that. “She’s doing her best, she can only do what they can let her do.” Genuine enthusiasm is very hard to find. Indeed, voters are already looking past her – she has the feel of a lame duck already.

Who would voters prefer to sort out the Brexit mess? Voters’ suggestions speak to what they feel is lacking at the moment. The suggestion of “Barack Obama – he’s a man of principle” from a former Corbynite ought to be worrying for the Labour leadership. And the suggestion of Jeremy Kyle indicates the scale of the hole that voters think we’ve dug ourselves: “if he can sort out the people that go on that programme, he can sort anything out.”