And he told BBC Scotland’s The Sunday Show that he would have no problem with Starmer “chapping on doors” if it helped secure success at the Holyrood election.
The Scottish Labour leader said: “I stand by what I said (for the prime minister to resign). I’m very clear about my opinion.
“It’s for other people in other parts of the UK to state their views.
“I care about one place – Scotland. And I care about one election – the one on the seventh of May.
“And I care most about changing one person out of office, and that’s the first minister’s office because this country is desperate for a different direction.”
Sarwar added: “If he (Sir Keir) wants to come and chap doors, as a Labour party member of course he would be welcome to come and encourage people to vote for me to become first minister.
“But what I do want ministers to be doing is delivering for Scotland.”
Scottish Conservative deputy leader Rachel Hamilton said Sarwar was “trying every trick in the book to distance himself from Keir Starmer, but Scots will not be fooled”.
She added: “With three of his Scottish Labour MSPs currently suspended, Sarwar’s party are engulfed in the same levels of sleaze as their counterparts in Downing Street.”