Stephen Flynn has attacked the Conservatives and Labour for their continued support of Brexit.
The SNP leader at Westminster asked Rishi Sunak when his party and Labour were finally "going to realise that Brexit can't work" during PMQs today.
He also asked Sunak what "worries" him most about Brexit.
Flynn suggested that it may be the hit to productivity or the prospect of former Tory leaders Boris Johnson, Liz Truss and Iain Duncan-Smith voting against the Northern Ireland Brexit deal.
Flynn said: "What worries the Prime Minister most about Brexit now? Is it the likely four per cent hit to UK productivity? Or is it three former Tory leaders planning to vote down his deal this afternoon?"
There was some confusion in the House as many MPs and speaker Lindsay Hoyle believed Flynn was talking about Theresa May rather than Duncan-Smith.
Sunak replied: "The Windsor Framework represents a good deal for the people and families and businesses of Northern Ireland, it restores the balance of the Belfast Good Friday Agreement and ensures Northern Ireland's place in our precious union.
"What I would say to him: I was more intrigued by the words of his own party's president, who just this past week, has described his own party as being... in a tremendous mess."
SNP president and acting CEO Mike Russell said that the party was in a "tremendous mess" after head of media Murray Foote and CEO Peter Murrell resigned within hours of each other.
The pair resigned after it emerged the party had misled journalists over its membership figures.
Flynn then accused MPs of focusing on Brexit rather than other issues.
He said: "The reality is that while Westminster is once again consumed by the damage being cause by Brexit, the public at home are facing the biggest fall in living standards ever, the highest tax burden since the end of the Second World War and inflation at 10.4 per cent.
"When are the Conservative Party, and indeed, the Labour Party, going to realise that Brexit can't work?"
The Prime Minister replied: "The actions that this Government are taking is ensuring that full half of most families' energy bills are being supported by this Government.
"We're also making sure that we're delivering for people [by] cutting NHS waiting lists and that's something that we're happy to work with the Scottish Government to learn and share best practice with them on.
"But we're also delivering on the people's number one priority which is to stop the boats and end illegal migration."
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