Theresa May has played down polling that puts her on course to lose the General Election.
The Prime Minister insisted the only poll that matters is the June 8 vote after the seat projection study suggested the UK faces a hung parliament.
The constituency-by-constituency estimate for The Times by YouGov indicates the Conservative Party could lose 20 seats and see its majority wiped out, while Jeremy Corbyn's Labour may gain 28 seats.
The analysis is based on a complex model and suggests Mrs May's gamble of calling a snap election in the hope of a landslide win could backfire spectacularly.
During a visit to Plymouth Fisheries, where she met local fishermen, Mrs May said: "The only poll that matters is the one that's going to take place on June 8 and then people will have a choice as to who they want to see as leader, who they want to see as prime minister taking this country forward in the future, me or Jeremy Corbyn.
"I have the plan for the Brexit negotiations but I've also got a plan to build a stronger and more prosperous Britain and I'm confident we can do that because I believe in Britain and I believe in the British people."
YouGov's analysis puts the Tories on 310 seats, down from the 330 they went into the election campaign with, and 16 short of a majority.
Labour would get 257 seats, up from 229, the Liberal Democrats 10, up from the nine Tim Farron's party held when the election was called, the SNP 50, the Greens one and Plaid Cymru three.
Those figures are from the model's central estimate, which acknowledges a large range of variation.
A good night for the Tories could see Mrs May's party pick up 345 seats - a net gain of 15 but still well short of the kind of majority she would have hoped to secure following the decision to go to the country.
A bad night could see the Conservatives plummet to 274 seats.
YouGov's model draws on the data collected from around 50,000 panellists quizzed on their voting intention over the course of a week and uses a recently-developed technique called multilevel regression and post-stratification (MRP).
The pollster's MRP model is based on the fact that people with similar characteristics tend to vote similarly, but not identically, regardless of where they live.
During the EU referendum campaign it consistently showed that more voters favoured Leave than Remain.
But YouGov acknowledged that models could not produce estimates as accurate as a full-scale poll in each constituency.
YouGov chief executive Stephan Shakespeare said the data could change dramatically between now and June 8.
"The data suggests that there is churn on all fronts, with the Conservatives, Labour and the Liberal Democrats all likely to both lose and gain seats," he wrote in The Times.
"Based on the model's current estimates, some seats are likely to change hands along EU referendum dividing lines.
"This is just a snapshot based on data from the past seven days and people can and do change their minds in the closing days of a general election campaign.
"Furthermore, it would not take a slight fall in Labour's share and a slight increase in the Conservatives' to see Theresa May returning to No 10 with a healthy majority."
Green Party co-leader Jonathan Bartley told the Press Association: "If we learned anything form the past two years it is that you can't predict what's going to happen. There are seismic changes happening, we see it with Trump in America, we saw it with the EU referendum.
"So, on one level, it isn't surprising that we are seeing big shifts in the polling. It's also an exciting time - the Greens could play a very pivotal role in what comes out after this election."