UK prime minister Boris Johnson faced anger from Conservative MPs representing former Labour seats on Monday over his government’s stance on an impending cut to the universal credit welfare benefit.

The government introduced a £20-a-week increase to universal credit in March last year at the start of the coronavirus pandemic. The uplift is due to end in April, but the opposition Labour party and some Conservative MPs want the increased rate to continue.

The Northern Research Group of MPs, a caucus representing many of those elected for the first time in seats in northern England and the Midlands, said cutting back the credit would be “devastating for the six million individuals and families who are already struggling to stay afloat”.

Labour forced a symbolic, non-binding vote on the issue on Monday evening, with just six Tories rebelling and voting with the opposition. Downing Street said Tory MPs had been ordered to abstain because it had no legal consequence. Chancellor Rishi Sunak has pledged to set out his policy on the universal credit uplift “in due course” before the policy expires at the end of March.

But Mr Sunak is determined to stop the “temporary” £1,000 annual uplift becoming permanent and has reminded Tory MPs that such a policy would have to be funded through painful tax rises.

“It would cost £6bn — that’s the equivalent of putting 1p on income tax and adding 5p a litre on fuel duty,” said one ally of the chancellor. “Hopefully this will help focus minds among Conservative colleagues on what we value most.”

Mr Sunak met Mr Johnson and Thérèse Coffey, work and pensions secretary, last Friday to discuss options, including continuing with the £1,000 annual uplift, tapering it away or offering a one-off payment to recipients of at least £500.

Newly elected Conservative MPs vented their fury on private WhatsApp groups about how the narrative had developed. Messages in the the “109 group” — which represents the 107 MPs elected for the first time at the last election — expressed concern that Mr Johnson was not listening to their worries.

One member of the group said 350 messages had been exchanged on the issue during one morning. “I’m completely fed up with being marched up the hill on deeply unpopular policies and being marched down again. Free school meals and schools shows our government is being run by [footballer and campaigner] Marcus Rashford and Twitter.”

Another MP said, “it’s not the policy that’s the problem. Nobody really thinks pushing UC up in the long term is a good solution — it comes at a colossal cost. We’re happy with Rishi’s decision to make it part of a broader settlement, but we’re not happy that no one is listening to our concerns.”

Many of the messages in the group over the last week were focused on what is seen as a disconnect between Mr Johnson’s Downing Street operation and the views of backbench MPs. “It’s increasingly obvious to the 109 group that No10 doesn’t understand, doesn’t care about the MPs or the places they represent,” one member said, summing up the mood in the group. Others blamed the whips’ office

In explaining the abstention vote, Mr Johnson claimed that he wanted to protect Tory MPs from the possibility of online bullying from leftwing activists, saying that this had happened after a previous Labour debate on free school meals.

The prime minister claimed in a WhatsApp message to Tory MPs at the weekend that Labour had previously used its “army of Momentum trolls last time to misrepresent the outcome and to lie about its meaning and frankly to intimidate and threaten colleagues”.

He also compared the supposed risk of abuse with events “seen sadly across the Atlantic”. Number 10 declined to say exactly what Mr Johnson meant.