Truss was supported by only 15% of respondents, while 37% of respondents found it difficult to answer, the poll said on Thursday.
The previous poll, conducted from September 6-7, immediately after Truss became the prime minister, showed that 25% of respondents supported her. Thus, her rating fell by 10%, while Starmer enlisted the support of another 12% of Britons.
In addition, the Labour Party increased its lead over the Conservatives in terms of support, the poll revealed, since the opposition is now supported by 54% of respondents, compared with 45% on 25 September.
According to the poll, the Conservatives' rating fell by another seven points and reached 21%.
The Labour Party’s lead of 33% is the highest figure since the late 1990s, the poll noted.
The survey was conducted from September 28-29.