Theresa May has insisted her Chequers proposals are not "dead", as she faced accusations her Government is "too weak and too divided" to ensure there is no hard border in Northern Ireland.
The Prime Minister vowed to protect the "precious Union of the United Kingdom" in the negotiations with the EU, despite questions over the Cabinet's support for her Brexit blueprint.
Jeremy Corbyn noted Mrs May had not mentioned "Chequers" in her recent update to the Commons and in her Conservative Party conference speech, and asked: "Does this mean the Chequers plan is now dead?"
Mrs May replied: "He asked me if the Chequers plan was dead, the answer is no."
The Labour leader went on to claim the Tories were too busy fighting among themselves to negotiate effectively with the EU.
"The Prime Minister and her Government are too weak and too divided to protect people's jobs, our economy or ensure there is no hard border in Northern Ireland," he said.
"So the Prime Minister has a choice: she can continue to put the Tory Party's interests first, or she can listen to unions, businesses, and put the interests of the people of Britain first."
He asked: "Which is it to be?"
Mrs May hit back, saying: "Labour can play politics, the Conservatives deliver for the people of this country."
Mr Corbyn said International Development Secretary Penny Mordaunt and Work and Pensions Secretary Esther McVey have refused to say they backed the Chequers plan, joking: "Maybe she could share a pizza with them and sort it out."
And he asked the PM to confirm Treasury legal advice to Cabinet that the Government would have to pay the EU a "divorce bill" of £30 billion even if no Brexit deal was secured.
Mrs May replied: "We've been very clear throughout the negotiations in relation to the financial settlement that led to the figure of around £39 billion following the December joint report, that this is a country that honours its legal obligations and we will do exactly that.
"I'd also remind members of this House that we've been very clear, as have the EU, that nothing is agreed until everything is agreed."
The Prime Minister also told the Commons that she remained committed to securing a "good deal" with Brussels that "delivers on the Brexit vote, but also a deal that protects jobs and livelihoods and crucially that protects the precious Union of the United Kingdom".
SNP Westminster leader Ian Blackford later urged the Prime Minister to negotiate continued membership of the single market and customs union to "avoid an economic catastrophe".
He said: "Prime Minister, go to Brussels and act in the interests of all citizens across the UK and negotiate to keep us in the single market and customs union, that will command the majority in the House of Commons."
Mrs May responded: "The proposal that we have put forward is one that delivers on the referendum vote but also ensures that we protect jobs and livelihoods across the United Kingdom."
Tory backbencher Steve Double later raised concern over the impact of Brexit on the tourism industry in Cornwall.
The St Austell and Newquay MP said: "The tourism and hospitality sector is very concerned that they will be able to continue to access the seasonal workforce they need once we leave the EU.
"Can the Prime Minister confirm what action the Government is taking to ensure this important sector for our economy continues to be able to access the workforce it will need?"
The Prime Minister responded by saying the Government would take "the needs of the British economy" into account when considering future immigration policies.