One MP complained the Labour leader had looked at “panic stations” after the party lost the red wall seat of Hartlepool in Thursday’s by-election.
Others warned that other, better news from elections held across the UK on “super Thursday” had been overshadowed after the leadership launched a reshuffle on Saturday, before all the results were known.
One MP said: “Why not wait a few days? I had always thought of Keir as cool and calm, even forensic, before this.”
Another said: “You could have weaved a more mixed narrative, except it was panic stations because of Hartlepool.”
The MP, from the moderate wing of the party, added: “It gave a gift to the Corbynite left and sewed seeds of doubts in the moderates.”
During a lengthy reshuffle, Sir Keir sacked his shadow chancellor and chief whip. But he was forced to give his demoted deputy Angela Rayner so many new roles she now has a 24-word-long job title.
Today, both tried to put their divisions behind them, going for a public cup of coffee in Westminster.
As Sir Keir attempts to draw a line under the events of the past few days, it is understood he will visit the sites of key election victories, including Wales, where Welsh Labour exceeded expectations, and the West of England, where the party won the mayoralty race.
He is expected to remain in London for tomorrow’s Queen’s Speech, however.
Earlier he told his shadow cabinet he took full responsibility for the Hartlepool defeat.
He was said to have told the meeting: “To be clear, I take responsibility. Nobody else. I lead the Labour Party and it is entirely on me.”
Sir Keir also said that Ms Rayner had “a big new role, taking the fight to the Tories.”
But the recriminations from the weekend continued.
The architect of one of the party’s key victories last week warned it had become “too cautious” under Sir Keir and had been penalised for it at the ballot box.
Andy Burnham, the re-elected mayor of Greater Manchester, said Labour should have set out more clearly how much it believes nurses and care workers should be paid.
He also accused his party of failing to back him sufficiently last autumn when he battled Boris Johnson’s government plans to pay people furloughed in his area just 67 per cent of their wages, rather than the 80 per cent that had been paid during a nationwide furlough scheme earlier in the year. Mr Burnham’s loud condemnation of the proposals made him a hero among many Labour activists.
He was re-elected at the weekend, taking 67.3 per cent of the vote. The size of his victory led to suggestions Mr Burnham could be a future leader of this party.
He played down that idea, telling the BBC’s World At One that he intended to serve a full second term.
Under Labour rules, the party’s leader must be an MP.
But Mr Burnham did have a message for the current leadership. “The problem we have had – there is a caution that stops people putting forward clear policies. On nurses’ pay, I thought we should have been clearer about exactly what we thought was the right level of nurses’ pay coming out the pandemic.”
Equally, on pay rates for those in social care, he said: “That’s a Labour issue where we should speak without caution, being really clear that it is just wrong that anyone looking after people’s relatives gets paid less than a real living wage.”
On his furlough row with the government, he added: “They were too cautious then in their response to that issue and they did not back me as strongly as they should have done.”