The outcome of the European Union referendum is getting too close to call.

There is a 35 to 40% chance that the UK will vote to leave the 28-nation bloc in the 23 June referendum, according to analysts at US firm IHS.

The odds calculation is the latest sign that the Leave campaign is gaining ground and that Prime Minister David Cameron can’t

The most recent poll showed there is only a 1% gap between people who will vote to stay in the EU and those who will vote to leave.

The ORB poll for the Telegraph in March found that that support for Remain is 49% and Leave 48%.

“Should the UK decide to leave the EU, the outcome of the move is dependent on terms of the exit,” said Howard Archer, chief European and UK economist for IHS Global Insight.

The company said the UK risks a “hard exit scenario” — meaning difficult and lengthy negotiations on exit terms with the EU — which could compromise Britain’s ability to sign free trade agreements with other countries.

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