In an emotional Piers Morgan interview, the Labour leader promised to come out fighting when life got back to normal and insisted he could turn the party around despite a series of disastrous polls.
His promise to arrest his party’s fortunes came in an interview that also saw him open up about the death of his mother and his father’s struggles afterwards.
Speaking on ITV’s Piers Morgan’s Life Stories, Sir Keir insisted things would get better.
He said: “Let me go out there, let me take the mask off because we've been living in restrictions.
“As we come out of this, it allows the space to open up, the pandemic allows the political space to open up and the restrictions allow me to open up.”
Sir Keir admitted things had not been perfect since he took over, but explained he would be speaking to voters who had left or didn’t support the party to win them around.
He said: “The biggest change we need to make is a Labour party that stops looking in on itself and looks out to the electorate and voters.
“I am going to go out and talk to the country this summer to people who are no longer voting Labour and hear for myself what they have to say and show that re-connection.
“We had to make changes on things like anti-Semitism. It was really important to me, to the party and I think to the country that we dealt with anti-Semitism.
“We've begun to do that. We are turning the party around.”
Sir Keir told the ITV host it had been a difficult for his party, but promised to build a better argument as to why people should vote Labour.
He said: “I am not going to pretend the last few weeks have been an easy, but there's a huge emotion that runs through the Labour party.
"We have a huge job, we need to make the persuasive argument as to why Britain would be better under Labour, we need to be patriotic and proud of it.”
The 58-year-old also fought back tears while discussing how his mother, born with Still's disease, died just three weeks before he was sworn in as an MP.
The disease is a rare type of inflammatory arthritis, with symptoms including fevers, rash and joint pain.
Sir Keir said: "It was really tragic. She would have loved to have seen that. But she was so ill by then.
"That was the stage in her life when she'd had her leg amputated. She couldn't move, she couldn't use her hands, so she had to be fed. She couldn't speak, couldn't communicate.
"I would have loved her to have been there, but she was in a terrible way.”
Sir Keir said his father lost interest in life after she passed.
He explained: “That devotion, that sense of duty, is very, very powerful. It was a life-long duty and when she died it broke him.”
The Holborn and St Pancras MP was also asked for a message for Boris Johnson, and replied: “Move over, we're coming.”