LONDON/BRUSSELS (Reuters) - British Prime Minister Theresa May’s Brexit strategy came under attack from all sides on Monday, putting in doubt her ability to steer any agreement through parliament and raising the risk of a disruptive “no-deal” exit from the European Union next March.

Britain's Prime Minister Theresa May returns to Downing Street in London, Britain, November 12, 2018. REUTERS/Simon Dawson

In a sign that Brexit talks could go down to the wire, EU sources said they want clarity from London by the end of Wednesday at the latest if there is to be a summit this month to approve a Brexit deal.

May’s compromise plan, which seeks to maintain close trade ties with the EU in the future, is facing opposition from Brexiteers, pro-Europeans, the Northern Irish party that props up her government, and even some of her own ministers.

“I think it’s the worst of all worlds,” former education minister Justine Greening, who supported staying in the EU in the 2016 Brexit referendum, told BBC radio, adding that she did not think there was any chance it could get through parliament.

A British official voiced pessimism about the possibility of a breakthrough with the EU this week due to continued deadlock on the issue of the border between British-ruled Northern Ireland and EU member Ireland.

Sterling tumbled to a 1-1/2 week low of $1.2827 on fears of a possible no-deal Brexit that many investors fear will weaken the West, panic markets and block the arteries of trade. It recouped some losses after the Financial Times said the main elements of a Brexit treaty were ready, though May’s spokesman said the report should be treated with scepticism.

“Technically speaking, the text is ready. But there is no political agreement from their side,” a senior EU diplomat said.

The EU’s chief Brexit negotiator Michel Barnier told EU ministers from the 27 other member states that “intense negotiating efforts continue”, adding that the Irish border issue remained unresolved.

Both sides want the border to remain invisible after Brexit but London says a suggested solution that would see the whole UK remaining in a customs area with the EU must have a clear time limit. Brexiteers fear the UK could be trapped indefinitely in the EU’s embrace, thereby frustrating British voters’ wishes.

The EU rejects any time limit to the so-called ‘backstop’ insurance policy to guarantee an open border. It is also demanding an agreement on fishing quotas and efforts to ensure a level regulatory playing field with the UK after Brexit.

LONDON CALLING

Economists polled by Reuters last week said there remains a one-in-four chance that London and Brussels will fail to reach a deal on the terms of departure.

Both sides need an agreement to keep trade flowing between the world’s biggest trading bloc and the fifth largest national economy.

But May has struggled to untangle nearly 46 years of membership without damaging trade or upsetting the lawmakers who will ultimately decide the fate of any deal she can secure.

If there is a breakthrough in the negotiations, a Brexit summit of EU leaders could be called for Nov. 24-25 to rubber-stamp it, diplomats said.

While May has for months faced fierce opposition from Brexit-supporting lawmakers, who say she has betrayed the referendum result by seeking such close ties with the EU, she is now facing increasing pressure from pro-Europeans too.

Jo Johnson, the younger brother of leading Brexiteer and former foreign minister Boris, resigned from May’s government last Friday, calling in a withering critique for another referendum to prevent her Brexit plans.

If a deal is voted down by parliament, the United Kingdom will face an uncertain future: leaving abruptly without a deal, the collapse of May’s government, an election, or, as some opponents of Brexit hope, a new referendum.

The EU is not currently working to include any second referendum in its Brexit planning, sources in Brussels said.

Brexiteers say leaving without a deal might be damaging in the short term but that in the longer term it would be better than signing up to obey rules from the EU for decades to come.

German Finance Minister Olaf Scholz said on Monday no country in the EU would escape unharmed from a no-deal Brexit, adding: “For Britain that would definitely be the worst option.”

Spanish Prime Minister Pedro Sanchez told the Politico news website that if he were Theresa May he would call a second referendum, saying he hoped Britain could rejoin the EU one day.