Boris Johnson is more trusted by Tory members to make big decisions and negotiate with the EU than Jeremy Hunt – as well as being regarded as more competent than the current foreign secretary – according to the latest Opinium poll for The Observer.

The findings reinforce Johnson’s position as the strong favourite to succeed Theresa May when Tory party members vote on who should be the next prime minister in the coming weeks. Last week Conservative MPs voted to send Johnson and Hunt into the final round of the contest.

Some 47% of Conservative voters say they would trust Johnson most to make big decisions, against 33% who choose Hunt. The gap is even wider on Brexit, with 57% preferring Johnson to negotiate Brexit than his rival who is chosen by just 26%.

When respondents were asked who was most competent, the result was closer, with 49% saying Johnson and 44% Hunt.

The polling was carried out last week before news broke that the police had been called to the London flat in which Johnson lives with his partner Carrie Symonds, following a late-night row between the couple.

The Opinium survey shows the extent of the challenge facing the next Tory leader. It puts Labour back in the lead on 26% (up 4 points compared with last month), while the Brexit party is second on 23% (down three) and the Tories languishing in third on 20% (up three). The Liberal Democrats are unchanged on 16%.

When given a binary option about next steps they would like to see on Brexit, almost half (48%) of UK adults now think the UK should leave the European Union with “no deal” on October 31st if the House of Commons cannot agree on a deal by then. Only 40% want to delay Brexit and hold a public vote.