The European Union’s chief Brexit negotiator, Michel Barnier, warned British Prime Minister Boris Johnson that he will have to to accept limits on access to the single market in return for greater control over fishing—or face no deal.

After his British counterpart issued a statement on Thursday night describing the talks as “blocked,” Barnier said a deal could be struck if both sides make “a real effort.”

But, in a speech to the European Parliament on Friday, he gave a stark assessment of the ultimatum the EU is giving to the British: access to the EU’s single market will be conditional on keeping British fishing waters open to boats from the bloc.

That puts him on collision course with Johnson, who said on Thursday the negotiations will fail unless the EU softens what he called its “not reasonable” stance on fish.

“If the U.K. wants to cut access to these waters for European fishermen, at any given time, then the EU also has to maintain its sovereign right to react or to compensate by adjusting the conditions for products, and notably fisheries products, to the single market,” Barnier said.

‘Moment of Truth’

The fishing industry has a minimal economic impact—it accounts for just 0.1% of U.K. gross domestic product—but is of high political significance, with Johnson’s government seeing it as a symbol of national sovereignty. By linking fishing to trade, the EU is betting that the U.K. will grant European boats better access to its waters in return for being able to do business with the bloc in other areas.

“We’re at the moment of truth,” Barnier told the European Parliament. “We have very few hours left if we want an agreement.”

Amid the rhetoric, officials in Brussels expressed confidence that a deal could still be struck before next week. Behind the scenes, the talks are progressing, and such negative language is to be expected at this stage, both as a negotiating tactic and to manage expectations at home, they said. In the meantime, the discussions continue.

There’s often an element of theater at the end of negotiations, Irish Deputy Prime Minister Leo Varadkar told RTE on Thursday. He said he was on the “optimistic” side of a 50:50 chance of a deal.

Sticking Points

The other major obstacle is the level competitive playing field for business. For months it looked like this was what could break the negotiations and while the issue isn’t completely resolved, the two sides are much closer to a solution, according to officials on both sides.

For some weeks, the U.K. has objected to the EU’s plan to exempt central bloc financing, including its 750 billion-euro ($920 billion) pandemic relief package, from any restrictions on state aid, according to a British official.

In a call with European Commission President Ursula von der Leyen on Thursday, Johnson said the U.K. was “making every effort to accommodate reasonable EU requests on the level playing field, but even though the gap had narrowed, some fundamental areas remained difficult.”

Johnson said that the EU’s position on fisheries was “simply not reasonable and if there was to be an agreement it needed to shift significantly,” according to a statement from his office. “The U.K. could not accept a situation where it was the only sovereign country in the world not to be able to control access to its own waters for an extended period.”

The two sides are battling it out over how long a transition period will apply before any new fishing rules and quotas take effect. The U.K. has pushed for three years; the EU wants longer. They are also still arguing over precise quota numbers and how often they should be renegotiated.

On Thursday, the European Parliament added to the pressure by setting officials a Sunday deadline to reach a deal for it to be ratified in time for the end of the transition period on Dec. 31.

In London, Cabinet Office Minister Michael Gove told a House of Lords committee that the negotiations could even continue after Christmas. He said the EU could provisionally apply any agreement, allowing it to delay getting the European Parliament’s approval until 2021.