The European Union’s plan to implement a financial-transaction tax may be called off soon if more countries back out, Austrian Finance Minister Hans Joerg Schelling said. “If there are more than nine member states, they can do it,” Schelling said in Vienna on Friday. “Probably next week we’re going to be down to seven, and that would mean we have to stop it.” Plans for a transaction tax already failed among all 28 EU nations, and the current talks are seeking a compromise among a smaller group that sought to press on under “enhanced cooperation” rules, which require consensus from at least nine nations. Schelling, who’s leading the talks, said 10 are still at the table. Efforts to agree on a joint European transactions tax have moved slowly in the past four years amid disagreements over which trades to tax and how to allocate the revenue. In December, Estonia left the negotiating group while 10 nations agreed on principles for going forward and set a mid-2016 deadline to reach a deal. In May, Belgian Finance Minister Johan Van Overtveldt signaled his country might pull out of the talks. Italy was said to be wavering, while Slovenia raised concerns over the viability of the plan. Schelling said Belgium and Slovenia are potential dropouts. The tax will be discussed on the fringes of a meeting of euro area finance ministers later this month, and Schelling said he will push for a decision. “In my view we need a ‘Yes’ or ‘No’ now,” Schelling told reporters. “I have already said in Brussels that I’m at my wits’ end.” Schelling also said he thought the U.K. would vote to remain in the EU in a referendum later this month. “I personally am sure that Great Britain will decide to stay in the union,” he said.