A handful of Tory MPs will vote against Boris Johnson on Monday over his plans to end soon the emergency increase to benefits for about 6m people which was put in place during the Covid-19 pandemic.

The prime minister authorised a £20-a-week increase in universal credit — amounting to £1,000 a year — to help the unemployed and low-income workers get through the crisis.

Keir Starmer, the Labour leader, has triggered an opposition day debate in the House of Commons in protest after Mr Johnson signalled last week that he would end the temporary measure in March.

While Tory MPs have been told to abstain in any vote that follows the debate, a small rebellion is expected in the “low double digits” — according to one backbencher. Those expected to vote against the government include Stephen Crabb, former work and pensions secretary, and Paul Maynard, former transport minister.

Dominic Raab, foreign secretary, said on Sunday that the measure was designed to look after the most vulnerable but was “always a temporary measure”. “We’ve got a March budget well before the end of the temporary uplift in UC, which is a chance to look at this in the round,” he told the BBC.

Rishi Sunak, the chancellor of the exchequer, has drawn up plans to give a one-off payment of £500 — or even £1,000 — to all UC recipients to try to draw a line under the row.

But one Tory MP said that a large single payment was “not the right way forward” because it would trigger demands from other interest groups.

Another said: “The government has made a rod for its own back. You can’t take away something you have given without paying a political price.”

Critics on the Conservative benches are divided over how long they think the increase in UC should continue. The Northern Research Group of MPs representing seats in the north of England likely to be hit hardest has, for example, called for a continuation but only until lockdown is lifted — which could be as early as March anyway.

Paul Maynard, a Blackpool MP, confirmed he would vote against the government. “I have been calling for some time now for universal credit to be uplifted. I hope the government are thinking carefully about how they can protect the incomes of those who have been hit the hardest,” he said.

The Child Poverty Action Group, a campaign group, warned that cancelling the increase would push 200,000 more children below the breadline.

Labour will argue in Monday’s debate that cancelling the increase will heap “unnecessary uncertainty” on families that are already struggling.

The debate in the Tory ranks over extending increases to universal credit comes as the Resolution Foundation warned that the main hit to UK living standards from Covid-19 will come in 2021.

The charity said government schemes had ensured real incomes did not fall in 2020. Universal credit had “protected incomes [of poorer families] during the pandemic so far,” it added, so long as they were eligible to receive it.

Withdrawing the UC uplift alongside a rise in unemployment meant “the living standards outlook for 2021 looks bleak at present,” according to Karl Handscomb, senior economist at the Resolution Foundation.

The charity expects real average after tax incomes to fall 0.4 per cent in 2021 with the UC decision helping to determine “whether this is to be a parliament of ‘levelling up’ living standards, or pushing up poverty,” according to Mr Handscomb.