Speaking during a visit to a housing development in Yorkshire, Sir Keir was asked whether the Prime Minister should give a full account of who knew what when about the election date.
The Labour leader said: “Of course he should. He should also suspend this candidate. As a candidate of mine, they’d be gone – their feet wouldn’t have touched the floor. And it’s very telling of Rishi Sunak that he hasn’t taken that action. But there is a bigger picture here.”
Describing the most recent reports as “astonishing”, Sir Keir added: “The Government and Rishi Sunak just need to take action. He needs to account for exactly who knew what, but when you’ve got a candidate standing for election in two weeks who’s involved, they’ve got to go – they’ve got to be suspended.
“I don’t know why he hasn’t done that. I think it is a real measure of his leadership, or lack of leadership.”
Mr Lee has taken a break from his role after it emerged that Ms Sanders is facing an inquiry by the Gambling Commission. She previously worked at Conservative Party headquarters.
The BBC reported on Thursday morning that she is married to Mr Lee. The latter’s LinkedIn page now appears to have been taken down. A summary on Google shows he was listed as the party’s director of campaigning.