The poll, which surveyed 1,712 adults on Wednesday and Thursday, comes as Ms Truss and Mr Kwarteng, the Chancellor, have struggled to reassure economists and the public alike about the merits of their economic strategy.
The lead is the highest of any recorded poll since the late 1990s, according to YouGov.
Voters also appeared more willing to pick Sir Keir Starmer when asked who would make the best prime minister, with 44 per cent choosing the Labour leader compared with 15 per cent for Ms Truss.
What will particularly worry the Conservatives is that only 37 per cent of 2019 voters said they would stick with the party at the next election.
Elsewhere, the poll puts the Liberal Democrats on seven per cent.
A further poll published on Friday lunchtime showed Labour with a 30-point lead, which will further stoke internal Tory fears about public perception of Liz Truss and her Government.
The survey was carried out by People Polling, a new firm led by pollster and academic Matthew Goodwin.
Sir Keir Starmer’s party is on 50 per cent – up 10 percentage points on the previous week – while the Conservatives are on just 20 per cent, down eight points.
The fieldwork, carried out on Thursday as Ms Truss launched a defiant public defence of her wave of tax cuts, puts the Liberal Democrats on nine per cent and the Greens on eight per cent.
While Ms Truss has said before that she is prepared to be an unpopular Prime Minister if it means delivering growth for the UK, the figures will nonetheless likely prompt serious questions about her leadership only weeks into the job.
