Opinium's is the latest in a series of polls to show a growing Labour lead after investors baulked at unfunded tax cuts in finance minister Kwasi Kwarteng's Sept. 23 fiscal statement, forcing the Bank of England to step in to stabilise markets.
The Opinium poll, based on a survey of 2,000 British adults between Sept. 28 and 30, showed support for Labour had risen to 46%, up by 7 percentage points since the last poll on Aug. 31-Sept. 2, while Conservative support dropped by the same amount to 27%.
Some 55% of those surveyed disapproved of the job Truss was doing, versus 18% who approved, a negative net approval rating of -37.
"Liz Truss has managed to reach the depths of the poor personal ratings of both Theresa May and Boris Johnson at the end of their tenure, within weeks of taking office and within days of her government's first major action," James Crouch, Opinium's head of policy and public affairs, said.
Truss succeeded Johnson as Britain's prime minister on Sept. 6, after defeating former finance minister Rishi Sunak in an election by Conservative Party members, but her first two weeks in office were overshadowed by the death of Queen Elizabeth.
Kwarteng's popularity has slumped too, with his net approval rating falling to -40 from -10, Opinium said.
(Reporting by David Milliken; Editing by David Holmes)