Members of the European Parliament have issued Brexit negotiators an ultimatum – get a finalized deal on their desks by midnight on Sunday or face the chances of it not being ratified by the end of the year.

In a statement, the Conference of Presidents said the parliament stands ready to call an extraordinary plenary session in late December "in case an agreement is reached by midnight on Sunday December 20," but added it was contingent on having access to a "provisional version" of the text "as soon as possible."

In a tweet before the statement was released, Manfred Weber, who heads the biggest political party in the parliament, said: "We owe it to the people and businesses in our constituencies who will be heavily affected by Brexit, to scrutinize the deal appropriately. After Sunday, we don't believe this would still be possible."

As the clock ticks down, MEPs are increasingly concerned their role in the Brexit process is being marginalized. Every day that passes is one day less they have to read the text, to scrutinize it, debate it and then vote on it. In any other trade negotiation, this would take around four months. Now it's being squeezed into mere days. 

And as the only elected officials in Brussels, MEPs don't want to be seen as rubber-stamping what could be the most consequential trade deal for years to come.  

Dacian Ciolos, president of Renew Europe, said UK Prime Minister Boris Johnson had until Sunday to make a decision. "The uncertainty hanging over citizens and businesses as a result of UK choices becomes intolerable," he tweeted.

Stumbling blocks remain 

The Sunday deadline was issued after the EU's chief negotiator Michel Barnier briefed the party presidents on the state of the negotiations on Thursday morning. In a tweet, he said "good progress" has been made, but the "last stumbling blocks remain." 

Across the Channel on Thursday, the UK minister Michael Gove told parliament that negotiators are working "day and night" to try to clinch a deal and that Britain was going the "extra mile" in talks.

"The UK government has been clear about the importance of maintaining sovereignty, the right to diverge and, indeed, full control over our waters," Gove said. "We shan't be ambiguous about that but we are determined, if we can, to reach a free trade agreement and our negotiators are working hard to that end."

On Wednesday, European Commission President Ursula von der Leyen said many of the differences on the issues of the so-called level playing field and governance had been bridged, but the fisheries discussions remained "very difficult." 

She added: "In all honesty, it sometimes feels that we will not be able to resolve this question."

While MEPs put a Sunday deadline on receiving the final text, they urged the Commission to hand over the draft version so they can get working on what is said to be a 1,000-page-long deal.  

It's unlikely the Commission will want to do that because it could create a "too many cooks in the kitchen" scenario, where MEPs could start pushing back on parts of the deal that aren't finalized yet, or worse, it could leak to the press.

The deadline piles more stress on what is a pressure cooker situation already. If the MEPs follow through with their threat, it could lead to no deal being in place come January 1, even if one has been agreed to.