Sir Keir Starmer and Lisa Nandy are the overwhelming favourites to be the next Labour leader among senior party figures in “red wall” seats, a Guardian survey has found.

Interviews with 33 Labour leaders in the party’s leave-voting former strongholds revealed widespread concern about the prospect of Rebecca Long-Bailey winning the contest, with many describing her as the “continuity Corbyn” candidate.

Sir Stephen Houghton, the Labour leader of Barnsley council, said “things had to change” and that voters would abandon the party unless it moved on from Jeremy Corbyn and Brexit. “We need to move back to the centre ground to make us appealing to a wider audience,” he said. “At the moment we’re not even appealing to our own heartlands.”

The Guardian survey is the most comprehensive barometer yet of the leadership contest in areas where voters defected in huge numbers to the Conservatives in last month’s general election. The poll includes leaders in six of the 10 longest-held Labour constituencies, such as Rother Valley in South Yorkshire, where voters backed the Tories in December for the first time in the seat’s 101-year history.

All but three of those surveyed said they were supporting Starmer or Nandy and the vast majority expressed strong reservations about Long-Bailey, a frontrunner who is backed by allies of Corbyn.

The endorsement of dozens of Labour council leaders is a significant boost for Nandy, whose polling lags behind Starmer and Long-Bailey. Jess Phillips had been a second choice for several local leaders before she withdrew from the race on Tuesday. None of those surveyed backed Emily Thornberry.

Long-Bailey’s campaign will not be surprised by her relative unpopularity with senior local figures, who were in many cases sceptical of Corbyn’s leadership from the beginning and some of whom have been in place since the Blair-Brown era.

Starmer has emerged as the early frontrunner in the contest after securing the backing of two major trade unions and 12 constituency Labour parties (CLPs). The backing from senior figures in leave-voting areas may come as a surprise given his vocal support for a second referendum before the general election, when he described Labour as the party of remain.

Graeme Miller, the leader of Sunderland city council, one of the most heavily leave-voting areas in the country, said his “gut instinct” was to back Starmer as the candidate that would appeal most to the public. “My focus has been looking at what we need, not what the membership wants. What the public will vote for has to be the focus,” he said.

Quick guide Who do senior Labour figures in 'red wall' seats want as leader? Show Hide • The “red wall” was a huge block of Labour-voting constituencies stretching from north Wales into Merseyside, through Greater Manchester along the Midlands and up to the north-east. The origin of the term is unclear but some believe it was first used in 2019. • Thirty-three Labour leaders spoke to the Guardian and all but three supported Sir Keir Starmer or Lisa Nandy to become the party’s next leader. All of the 33 local authority areas voted for Brexit in 2016. • Of those who would disclose their least favourite candidate, all but two said Rebecca Long-Bailey. The other votes were for Jess Phillips and Emily Thornberry. • Labour leaders in six of the 10 longest-held Labour seats that fell to the Tories said they were backing Starmer or Nandy. They are the Labour leaders in Rotherham, Newcastle-under-Lyme, Leigh, Bassetlaw, North East Lincolnshire and Bolsover. The other four leaders had not responded to requests for comment.

Many leaders felt Starmer was the most credible and competent candidate and would appeal to a broad church of voters, praising his legal background and clear public speaking.

Those who supported Nandy praised her ability to connect with voters outside the metropolitan bubble, particularly in post-industrial towns where people have felt left behind. Many said they were impressed by the Wigan MP’s forthright assessment of Labour’s future, which included warning fellow MPs that the party must change or “we will die and we will deserve to”.

While Long-Bailey may be popular among a large section of Labour members, dozens of local party leaders expressed concern that she would simply continue the “Corbyn project”. The Salford and Eccles MP was felt by many to have failed to properly reflect on the reasons behind Labour’s worst election result since 1935.

There was also concern among council leaders that the leadership contest had been too heavily focused on big cities instead of the provinces, where many Labour voters broke a decades-long tradition to back Boris Johnson’s party last month.

Pick Long-Bailey and it's over: the view from the ruins of Labour's red wall Read more

Some said the candidates needed to “get out more” and reconnect with voters; others complained that the main hustings debates were closed off from the public – with only party members eligible to attend – and hosted mainly in large cities such as Liverpool, Glasgow and Cardiff.

“I’m disappointed that the Labour party still doesn’t seem to be learning from the fact that we need to be getting out into towns not just cities,” said Kyle Robinson, the Labour opposition leader on Newcastle-under-Lyme council, where the Tories won majority control in 2017.

“The Labour heartlands are where we need to be going and not just inviting Labour members but inviting members of the public so they can ask questions of the people who want to be our next leader.”

Fewer than 20 CLPs have so far declared their support in the leadership contest, the winner of which will be announced on 4 April.

Starmer and Nandy have already made it through to the final ballot. Starmer won the backing of Unison, the UK’s largest trade union, and the environmental affiliate Sera, while Nandy secured the support of the NUM and GMB unions, and the Chinese for Labour affiliate. Under Labour’s leadership rules, candidates must have a certain amount of support from CLPs or affiliates (unions or socialist societies) to be sure of a place on the final ballot.