Labour MPs are urging the government not to weaken its electric vehicle targets as divided cabinet ministers prepare for a crunch meeting on Thursday to thrash out a compromise.

Members of the climate and nature crisis caucus (CNCC) say ministers must not water down a legal requirement for carmakers to ensure that 80% of the vehicles they sell in 2030 are electric, saying doing so would be a backward step and “shortsighted”.

The intervention comes as Louise Haigh, the de facto deputy prime minister, prepares to meet the energy, business and transport secretaries to decide whether to change the target. A meeting planned for Wednesday has been pushed back to Thursday, according to government sources.

Jonathan Reynolds, the business secretary, wants to slash the target to 50%, while Heidi Alexander, the transport secretary, wants to cut it to about 60%. Miatta Fahnbulleh, the energy secretary, is pushing for it to remain as close to 80% as possible.

Sources say Haigh, who is standing in for Andy Burnham after the prime minister recused himself over a potential conflict of interest, is likely to support a middle route and agree a new target of between 60% and 65%.

With a final announcement likely this month, Labour MPs are making a final push for ministers not to reduce the target, which many see as emblematic of the government’s approach to the green agenda.

Chris Hinchliff, the chair of the CCNC, wrote to Alexander on Tuesday saying that a decision to cut the 2030 target would be a “step backwards”.

“This would undermine the government’s wider net zero ambitions and our credibility as a climate leader on the world stage,” he added.

From left: Jonathan Reynolds, Andy Burnham and Louise Haigh watch an apprentice at work at the McLaren Technology Centre in Woking. Photograph: Stefan Rousseau/PA/AP

Arguing that reducing the target would undermine Burnham’s push to reindustrialise Britain, he said: “Diluting the mandate would be a backward-looking distraction from the urgent need for a coordinated industrial strategy.”

The Department for Transport has been contacted for comment.

Hinchliff is being backed by several other Labour members of the caucus. Clive Lewis, the MP for Norwich South, said: “We need more ambitious targets, not less ambitious ones. What this will say to the country is that we set these targets and then drop [them]. We need to show some consistency and ambition.”

Nadia Whittome, the MP for Nottingham East, said: “This is the government’s biggest decarbonisation policy. Watering it down would carry serious environmental consequences and it wouldn’t help the cost of living.”

Some Labour MPs from industrial areas are backing cuts to the target. Antonia Bance, the MP for Tipton and Wednesbury, said: “A 50% ZEV target by 2030 would give manufacturers a more realistic pathway while still keeping us on track for net zero.

“We can cut emissions and create the cars of the future – but we also need to protect good jobs, investment and supply chains here in the UK.”

Others in the party, however, are concerned that decisions such as weakening the EV policy and approving the Jackdaw gasfield are undermining the government’s green credentials and could risk boosting the Green party.

“Climate is not something that seems to be close to Andy [Burnham]’s heart,” said one MP. “Decisions like the EV mandate and Jackdaw develop a sense, which the public pick up, that we are not very progressive.”