The SNP Westminster leader on Wednesday questioned whether the Prime Minister had the support of his party and suggested Mr Johnson he had shown the worst of the Tory party.
Speaking at a fiery Prime Minister’s Questions, Mr Blackford also joked about Mr Johnson’s CBI speech, which saw him lose his place and discuss a visit to Peppa Pig World on Monday.
Mr Blackford said: “The past few weeks have shown this Tory government at its very worst.
“A Tory sleaze and corruption scandal, on a scale not seen since the 1990s.
“Tory cuts and tax rises that will leave millions of people worse off.
“A litany of broken promises – from HS2, to carbon capture, social care, the triple lock on pensions – and, who can forget, the £20 billion bridge to Ireland that evaporated into thin air.
“At the centre of all of this is one man, a Prime Minister who is floundering in failure.
“So can I ask the Prime Minister, with his party falling in the polls and his colleagues briefing against him. Has he considered calling it a day before he’s pushed out the door?”
The Prime Minister said: “I think what the people of this country want to hear is less talk about politics … and they want to talk about what the Government is doing for the people of Scotland, and what the Scottish Government is doing for the people of Scotland, which isn’t enough.”
Mr Johnson said later in the week the Westminster Government would be setting out “what we’re going to do with the union connectivity review to ensure that the people of Scotland are served with the connections they need”.
But Mr Blackford accused the Prime Minister of never taking responsibility and being unable to deliver a “coherent speech”.
The Ross, Skye and Lochaber MP said: “The Prime Minister's officials have lost confidence in him. Tory MPs have lost confidence in him. And the public have lost confidence in him.
“Why is he clinging on, when he's so clearly not up to the job?”
The stinging attack came in a Commons session that saw Sir Keir Starmer accuse Mr Johnson of fronting a “pick-pocketing operation” to introduce a “working-class dementia tax”.
The Labour leader repeatedly pressed the Prime Minister over whether people would have to sell their homes as a result of the Government’s social care plans for England.
The Government wants to introduce an £86,000 cap on lifetime care costs from October 2023.
But a policy paper last week showed only personal contributions would count towards that cap for people who received financial support from a local authority for some of their care.
Sir Keir said: “The only thing he is delivering is high taxes, high prices and low growth. I’m not sure the Prime Minister should be shouting about that.
“And it isn’t just broken promises, it’s also about fairness. Everyone needs protecting against massive health and care costs.
“But under his plan, someone with assets worth about £100,000 will lose almost everything, yet somebody with assets of about £1 million will keep almost everything.
“He’s picked the pockets of working people.”