Speaking after the dramatic suspension of his predecessor – after he challenged the damning equality watchdog’s report – the Labour leader said the decision had been taken by the party’s general secretary, not him.
Asked if there was a way back for Mr Corbyn, he said: “It’s not my process it’s the party’s process – and what I mustn’t do is express a view on what should happen in the case.”
And, asked if, like Luciana Berger the former Labour MP hounded out of the party, he considered him “antisemitic”, Sir Keir replied: “I don’t see Jeremy Corbyn in that light.”
He also played down fears of a Labour split, insisting: “I don’t think it is necessary and I don’t think it will happen.”
The leader faced a torrent of questions after Labour was plunged into turmoil by Mr Corbyn’s suspension for claiming antisemitism under his leadership was “dramatically overstated for political reasons".
The party believed it had to act after all Sir Keir had said anyone who claimed discrimination against Jewish people was “exaggerated or factional are part of the problem”.
But the grassroots leftwing group Momentum condemned “a naked attack on the left that undermines the fight against antisemitism and makes a mockery of Keir Starmer’s pledge to unite the party”.
And Len McCluskey, whose Unite union gives millions to the party each year, warned on Thursday night “chaos” which would “compromise Labour's chances of a general election victory. A split party will be doomed to defeat”.
But by Friday, leaders of the left appeared to be backing away from open conflict with the leadership.
Mr McCluskey told Sky News: “It’s a sensitive time, I thought it was wrong what’s happened but now is the time for some calmness so we can see if we can resolve this.
“We need the party to be united, working people out there need us, need a Labour government, so stay in the party and I’m hoping that we will be able to get through this fairly quickly to everybody’s satisfaction.”
And former shadow chancellor John McDonnell said: “Keir Starmer this morning has rightfully said he doesn’t want a civil war in the Labour Party.
"Let’s be clear. Nobody does, but it seems we are drifting towards a hell of a row over use of language, misinterpretation, followed by over-reaction… My advice is that with a bit of explanation over what was meant in various statements we could all save ourselves a lot of unnecessary grief and get on with tackling Covid and job cuts.”
MPs on the left of the party, including Diane Abbott, were circulating a petition demanding Mr Corbyn’s reinstatement.
Labour’s youngest MP, Nadia Whittome, send a message of solidarity to the former leader and said his suspension “appears unjust”, though she also told Mr Corbyn that she disagreed with his response to the EHRC report.
Asked if he was carrying out a 1980s-style “Militant purge”, Sir Keir said: “I am not purging anybody or any group within the Labour party” – while insisting he would “not tolerate antisemitism full stop”.
Later, he added: “There is no reason for a civil war, there is no reason to lean inwards. That is not what I want. I want to unite the party.”
He revealed he had told Mr Corbyn, on Wednesday evening, that he would warn that anyone denying the antisemitism problem would have no place in Labour – but Mr Corbyn rejected the report regardless.
On Mr Corbyn’s personal culpability, Sir Keir stressed how the Equality and Human Rights Commission’s findings were a “collective failure of leadership”.
“It’s very important to recognise that, in the report we received yesterday, there were no individual findings against Jeremy Corbyn,” he said.
The EHRC report found three breaches of the Equality Act, involving harassment, political interference in antisemitism complaints and inadequate training for those dealing with cases.
Asked why he had not quit Mr Corbyn’s frontbench, Sir Keir said he had challenged what was going on and demanded reform, adding it was “important to have voices in the shadow cabinet”.