Wales has more at stake as a result of Brexit than any time since the Second World War, Labour has claimed.
During the Welsh affairs debate, shadow Welsh Secretary Christina Rees said industry's future and families' ability to get by "hangs in the balance".
The debate, on Monday night, was due to be held earlier this month but was postponed because of snow and storms.
Welsh Secretary Alun Cairns told MPs UK ministers had listened to the devolved governments' concerns on Brexit.
Mr Cairns pointed to the amendments made to clause 11 of the European Union (Withdrawal) Bill.
The clause, voted through the Commons at the end of last year, established that powers currently exercised by devolved governments within EU frameworks would be returned to Westminster.
Mr Cairns said the UK government was still working with Cardiff to get an agreement on the clause, but added: "We are very close to the deal."
In her speech for Labour, Ms Rees said: "I doubt there's ever been a St David's Day since the Second World War where there has been so much at stake for Wales.
"The future of whole sectors of industry as well as the ability of families simply to get by hangs in the balance.
"The people of Wales have a right to see a UK government acting in their best interests, protecting their jobs, investing in the public services they rely on and the infrastructure we desperately need to secure Wales's future."
Earlier, Mr Cairns explained changes to clause 11 which had emerged in the Lords.
He told MPs: "We've tabled an amendment so the assumption is that the legislation should be devolved with an order making power to enable the UK government working with all the devolved administrations to legislate and to protect the UK common market.
"The vast majority of powers returning from Brussels that intersect with devolved competence will fall under full control of the devolved administrations from day one of exit."
Plaid Cymru MP Liz Saville Roberts said that there appeared to be no "formal" way for these powers to be transferred.
Mr Cairns said "Whatever legislation comes out of those 24 areas of law that we want to use to protect the UK market, we will always seek agreement with the devolved administrations."