David Cameron is making key concessions on the EU Referendum Bill following pressure from Tory rebels and the SNP.
With a potentially embarrassing series of votes looming tonight, the Government has dropped the idea of holding the poll on the same day as elections in Scotland next May.
Movement is also expected on plans to scrap the "purdah" period running up to the in-out referendum, with ministers set to promise a "code of conduct" to ensure the Whitehall machine is not used to skew the vote.
The late shift came after whips seemingly realised they were on course for defeat on the matter of the date - with Labour, the SNP, some Conservative backbenchers, and the DUP joining forces to oppose doubling up with elections.
A senior government source said: "We've listened to the views expressed from MPs across the House and agreed that we won't hold the referendum on the same day as legislature elections.”
SNP foreign affairs spokesman Alex Salmond said ministers tabled their own amendment onlywhen it became evident they faced “retreat or defeat”.
"It was clear that the Tories were angling to hijack Scottish elections with the EU referendum and the united opposition have blown them off course,” he said.
"This is very much the shape of things to come and has hopefully taught this arrogant Tory government to cease their disrespect towards the nations of Scotland and Wales and the people of Northern Ireland.”
Conservative Eurosceptics have tabled amendments to the Bill that would reinstate the standard 28-day purdah restrictions laid down by the Political Parties, Elections and Referendums Act 2000.
However, Downing Street has been arguing that the rule will cause particular problems in this case because of the volume of day-to-day government business which involves the EU, and the need for the Prime Minister to make Commons statements on European issues.
Efforts have been ongoing to hammer out a purdah “framework” that will satisfy concerns on both sides, and ministers are expected to pledge a “code of conduct”.
However, it is unclear whether the concession will be enough to assuage the rebels. Former environment secretary Owen Paterson - one of the ringleaders - said last night that he was still “hoping for a rethink”.
The Government’s position has been strengthened after Labour indicated that its MPs will be ordered to abstain in the key vote - significantly reducing the chances of defeat.