The Conservative Party may be facing its worst election defeat in history as a mega poll involving more than 10,000 respondents suggested the number of Tory MPs in Parliament may be reduced to just 66 in July.

The large-scale survey carried out by pollsters Electoral Calculus and Find Out Now between May 20 and 27 forecasted Labour could secure nearly 500 seats on July 4, depending on whether UK citizens decide to cast their vote tactically.

A scenario in which tactical voting is applied to the top two parties in each new seat according to the implied 2019 General Election result would see Rishi Sunak‘s party electing only 66 Conservative MPs.

In turn, under this model, Labour has been predicted to win 476 seats – handing Sir Keir Starmer an even bigger landslide than Tony Blair’s in 1997, when Labour got 419 seats.

Without tactical voting, the Conservatives would perform slightly better, earning 72 MPs – but so would also Labour, winning an estimated 493, the poll carried out for the Daily Mail using the multilevel regression and post-stratification (MRP) method suggested.

While the Tories would still be the main Opposition, the mega poll indicated the Conservative Party would only hold a handful of seats more than the Liberal Democrats, forecasted by these pollsters to get 39 MPs elected without tactical voting and 59 in the stated scenario where tactical voting is present.

The SNP would also benefit slightly from tactical voting, according to this poll, earning 26 MPs. It is forecasted to get 22 MPs should people not vote tactically.

Plaid Cymru has been forecasted to get between three to four MPs, while the Green Party would trail behind, electing two MPs in any scenario adopted in the analysis.

Reform UK is not projected to win any seats under any scenario. However, the mega poll suggested the party could get 12 percentage points, splitting the right-leaning vote in dozens of seats.

Looking at the percentage points forecasted by these pollsters for the three largest British parties, Labour could get 46 percent while the Tories would get 19 percent. The Lib Dems have been forecasted to pick up 10 percent of the votes.

This Tory wipeout scenario would result in several high-profile Conservative MPs losing their seats.

Among them would be 18 Cabinet Ministers, including Deputy Prime Minister Oliver Dowden, Home Secretary James Cleverly, Defence Secretary Grant Shapps, Leader of the House of Commons Penny Mordaunt and Business and Trade Secretary Kemi Badenoch.

Claire Coutinho, Mel Stride, Gillian Keegan, Mark Harper, David Davies, Victoria Prentis, Esther McVey, Andrew Mitchell and Johnny Mercer have also been tipped by this analysis to lose their seats to Labour MPs.

Alex Chalk and Michael Tomlinson would lose to the Lib Dems, while Alister Jack would be replaced by an SNP MP and Simon Hart would lose to a Plaid Cymru MP.

Until Parliament dissolved this week, the Conservative Party held 348 seats, Labour 200 and the Lib Dems 15.