By staging a referendum on UK’s EU membership, David Cameron has chosen to “play with fire” and may find he is entirely dependent on the decisions of Labour voters to avoid finding himself badly burnt, a leading poll analyst has concluded.

John Curtice reached the verdict in a new study underlining the risks Labour and the Conservatives face in the coming months.

Writing for Juncture, the journal of the Institute for Public Policy Research thinktank, Curtice said that advocates of the UK remaining in the EU are leading by 53 % to 47%, excluding don’t knows, on the basis of an average of 20 Britain-wide polls. Two polls conducted by phone show the stay-in camp much further ahead.

Curtice, who masterminded the successful 2015 general election exit poll, finds that, on average, the most recent polls found that just 38% of Conservative voters say they will vote to stay in, while 49% say they are inclined to vote to leave.

John Curtice was writing for the journal of the Institute for Public Policy Research thinktank. Photograph: Martin Argles/The Guardian

Curtice concludes: “Cameron is at risk of becoming a leader who is seriously adrift of the mood of much of his party’s membership, and could well find himself leaving his party just as divided and as bruised over the issue of Britain’s membership as it was when he first became leader nearly 10 years ago.”

Curtice claims there is no definitive way of deciding how far voters’ minds will be shifted by a recommendation from Cameron that his negotiating objectives have been achieved, but much will depend on what concessions the prime minister extracts in his negotiations with European leaders.

He points out that a recent Survation poll found that only 5% of Conservative voters think that the most important thing that Cameron needs to achieve is to safeguard the position of the non-eurozone countries in the EU, while those prioritising cutting business regulation, securing an opt-out from “ever closer union” or giving national parliaments a greater role in the passage of European legislation also all stand at just 5%.

Priority for 22% of Conservative voters is action to deprive EU migrants of benefits, the issue that Cameron has clearly so far failed to resolve. Its popularity is matched by items that are not on Cameron’s shopping list, such as giving the UK parliament a veto over European legislation (24%) and ending freedom of movement (19%).

David Cameron’s list of renegotiation topics isn’t in line with the majority of his party’s membership. Photograph: GmbH/Rex Shutterstock

The polling, Curtice concludes, leaves Labour critical to the outcome, but also in the firing line if it misjudges the campaign. He says, on average, polls show 60% of those who voted Labour in May indicated they would vote to remain, while just 27% said that they would prefer to leave.

But he warns that Labour faces a specific problem. He writes: “Every poll finds that the idea of leaving appeals primarily to those in working class and less affluent households, while the stay-in camp is primarily populated by those in relatively secure middl class jobs.

“On average, nearly half (47%) of those in the lowest D/E social grade say that they want to leave, while no more than 36% would prefer to remain. In contrast, no less than 58% of those in professional and managerial A/B occupations are in favour of remaining, while just 31% wish to leave.

“If Labour is seen as advocating continued membership too enthusiastically, Labour’s predominantly middle-class parliamentary party is at risk of appearing out of touch with the working class, less affluent section of British society whose interests the party claims to stand for.”

Moreover for Labour voters, stopping EU migrants from being able to access welfare payments is at least as important as it is for Conservative voters, with nearly a quarter saying it is their top priority.

Curtice warns: “If Labour was to come to be seen as a principal cheerleader for remaining in the EU, that could be a development from which Labour suffers just as much as the Conservatives. Cameron may indeed be playing with fire, but Labour cannot afford to presume that its own house is fireproof.”