Leaving the EU is a complicated business. Hundreds of laws and agreements; and numerous pan-European bodies the UK is involved in. A lot to sort out.
Some Brexiteers would prefer no compromise with the EU, leaving with no deal.
I believe that option would cause chaos for business and for Britons with families or property in Europe.
The UK needs a deal. It won't be perfect. Theresa May could have sought a cross-party approach from the beginning. She didn't. And Cabinet divisions briefed out to the media don't help our negotiating position either.
This week, the House of Lords made things worse by amending the EU (Withdrawal) Bill to give Parliament a new option over the final deal. In addition to voting to accept, or to reject and leave with no deal, the Lords added the option to vote the deal down and keep the UK in the EU.
If I was Michel Barnier, the temptation to offer the worst possible terms in the hope that Parliament votes to reject it and stay in would be hard to resist. Hardly helpful to the UK achieving the best deal.
This is about our national interest. Do we want a good deal to pave the way for an orderly Brexit; free of cliff edges and crises? Or do we want to create the conditions to undermine Brexit and do so by weakening the UK's negotiating stance?
The Lords went further, adding an instruction that "Her Majesty's Government must follow any direction in relation to the negotiations" - the first time Parliament has ever sought to mandate a UK Government over treaty negotiations.
The Lords would empower Parliament to issue the Prime Minister with a shopping list of demands to take back to Europe. How feeble would that make the UK look? Next week, the Lords considers amendments to allow exit day - March 29 2019 - to be postponed.
All becomes clear. If Brexit cannot be defeated today, postpone Brexit by a year, maybe two, until, perhaps, an opportunity arises to overturn Brexit altogether.
Extending Brexit day by three months or longer would leave the UK facing elections to the European Parliament in May 2019; electing new MEPs months after we should have left.
Parliament should reject this game playing, and accept the country's decision. We are leaving.
I campaigned for Remain in the 2016 EU referendum. We lost. The country would probably have made the same decision had the referendum been held at any time in the previous decade.
There are some Remain voters so passionate that they want to fight, fight and fight again. But that is not most people. Most feel we should get on with it. So, it would appear, does business: the PSA group building new cars in Luton; Nissan in Sunderland; bank HQs staying in the City. Business investment grew in the year after the referendum, planning for UK post-Brexit. So should MPs.
In their hearts, the "stop Brexit" campaigners know the decision is made. Nevertheless, the campaign for "a People's vote" (a second referendum) is under way. I've had MPs in Remain-voting seats saying that this risks raising expectations, only for further disappointment.
And if there were a second referendum, why not a third? Endless uncertainty cannot be an option.
Two thirds of Labour MPs represent Leave-voting areas. Much is made of Leave areas losing out from Brexit. But the North, the coalfields, have lost out for many years, while bigger cities and the South East have prospered.
If Labour fails to stand by the 2016 vote, we risk alienating many traditional Labour voters. We should all heed the warning from Thursday's local elections.
In Sunderland, Amber Valley, Nuneaton, Derby, Dudley and Redditch, opinion moved to the Conservatives.
If Labour stood strongly behind the decision to leave the EU, we could champion the need for new policies to improve skills; build new infrastructure; ensure regional development; have effectively managed migration and a close relationship with Europe. In short, showing that Labour has a plan for the whole country; the very policies needed to restore faith among voters.
The Lords may play parliamentary games over Brexit; the Commons should not emulate them. The Brexit games have to stop.
Caroline Flint is the Labour MP for Don Valley and a former Europe Minister