LONDON (Reuters) - British employers are their most pessimistic about the outlook for the economy since last year’s Brexit vote and want clarity about the departure from the European Union, a survey showed on Wednesday.

FILE PHOTO: Workers are seen in office windows in the financial district of Canary Wharf in London, Britain, November 3, 2015. REUTERS/Kevin Coombs/File Photo

However confidence in hiring and investment remained stable this month, the survey by the Recruitment & Employment Confederation, representing recruitment firms, showed.

“The political climate isn’t helping the situation. Businesses need clarity in order to plan effectively, and so far the Brexit negotiations have not resolved any of the core issues,” REC chief executive Kevin Green said.

With 18 months to go before Britain’s scheduled departure from the EU, little progress has been made in negotiations.

British Prime Minister Theresa May is due to give a speech about Brexit on Friday, seen as a bid to put the talks back on track and fill an apparent policy vacuum.

She may also seek to reassert her authority, days after foreign minister Boris Johnson laid out his own Brexit vision, challenging her more cautious approach and exposing the fault lines in the government that have added to the uncertainty.

Green said he hoped for a quick deal on the status of EU nationals already working in Britain.

Britain’s economy slowed in the first half of 2017 as rising inflation, pushed up by the fall in the value of the pound since the Brexit vote, ate into households’ spending power.

So far, there has been little sign in official data of an offsetting effect from higher exports or more investment.

Open Britain, a pro-EU campaign group, said the survey showed businesses were losing confidence in the government’s plans for Brexit.

“Their plan for a crackdown on immigration from Europe will leave employers and our National Health Service short of the workers they need,” Pat McFadden, a Labour Party lawmaker who supports Open Britain, said in a statement released by the group.