Only 25% of voters thinks Jeremy Corbyn is decisive, according to a survey, down from 31% in October. The Labour leader’s fall to his lowest score at any point since the 2017 general election came despite most voters seeing the Tory party as divided following a week of Brexit infighting.

Corbyn also recorded his lowest score for being trustworthy and someone that sticks to his principles, according to an Opinium poll of 2,016 adults online on 13 and 14 December, falling below the prime minister.

The poll found that more than two-thirds of voters regarded the Tory party as divided following a week of infighting that included an attempt to topple Theresa May. Some 69% of voters saw the party as split, up significantly from 54% in October. In contrast, less than half of voters (47%) now see Labour as divided – the lowest proportion for a year.

The perception of the Tories as deeply divided comes in the wake of the confidence vote in May’s leadership called by Conservative MPs this week. The polling suggests the vote may have backfired on those who called it. The move was unpopular among Conservatives, with 57% of Tory voters thinking it was wrong. A majority of both Tory leavers and Tory remainers were against the vote.

However, some 37% of Conservative voters think Tory MPs should vote down the Brexit deal, up from 27% last month. Only 17% of all voters believe the UK is likely to emerge with a satisfactory deal.

However, the party closed Labour’s overall lead from three points last month to just one point. The poll put Labour on 39% of the vote, with the Tories up two point on 38% – after potentially having gained ground among Leave voters.

Some voters reacted favourably to May after her tumultous week: almost half (47%) of voters now see her as brave, up from 43% in October, while 41% see the prime minister as decisive – the highest since the election last year.

Theresa May and Jean-Claude Juncker have 'frosty exchange' – video

Almost half (47%) see May as someone who sticks to their principles, the highest figure recorded for her and the first time she has overtaken Corbyn on the measure. Approval for the way the prime minister has handled Brexit is low, but slightly higher than last month, with 53% disapproving and 28% approving.

Meanwhile, with Labour divided over its Brexit policy and as pressure grows from MPs to back a second referendum, support for the way Corbyn is responding to Brexit is low and falling. This month only 16% approve of his handling of the issue, against 55% who disapprove. Last month, 19% approved and 50% disapproved.