Jeremy Corbyn has described the government’s economic analysis of the Brexit deal as “meaningless” in exchanges at prime minister’s questions on Wednesday, as Theresa May denied that the country would end up poorer under her deal.

In testy exchanges in the Commons, Corbyn said: “MPs are queuing up not to back her plan.” More than 90 Conservative MPs have publicly confirmed they will not back the proposal.

In turn, May said her deal was backed by “farmers in Wales, fishermen in Scotland, employers in Northern Ireland”, adding: “When MPs come to look at this vote, they will need to look at the importance of delivering Brexit in a way that protects jobs.”

May said analysis released by Whitehall showed the country would be “better off with this deal” and said it did not show that people would be worse off.

“The biggest risk to our economy is the right honourable gentleman [Corbyn] and his shadow chancellor,” she said.

Corbyn hit back at the prime minister’s claims that the deal was the best on offer. “It’s not hard to be the best deal if it’s the only deal. By definition, it’s also the worst deal,” he said.

He criticised the analysis of the impact of the deal as outlined in the political declaration, saying it was not legally binding. “There is no actual deal to model, just a 26-page wishlist,” he said.

May said it was untrue to call it a wishlist and that it was politically binding on the EU, setting out “an ambitious broad, deep and flexible partnership across trade and economic co-operation, law, foreign policy, security and defence and wider areas of cooperation”.

“What does Labour have to offer? Six bullet points. My weekend shopping list is longer than that,” she added.

Corbyn said the prime minister would not conclude those future partnership negotiations in two years. “She has gone from guaranteeing frictionless trade to offering friction, less trade,” he said. “After these botched negotiations the country has no faith in the next stage of even more complex negotiations being completed in just two years.”

May said her negotiators had proved predictions wrong before, turning the 16-page December joint agreement into a legal withdrawal agreement of more than 500 pages in less than a year.

“At every stage people have said that we couldn’t do what we did… it takes hard work and a firm commitment to work in the national interest and that’s what the government has,” she said.