David Cameron has agreed to call an emergency cabinet meeting on Friday if he secures a renegotiation deal at this week's European Union summit in Brussels.
The move is an important concession to Eurosceptics in his Conservative Party, because it will allow cabinet ministers to immediately speak out in favour of leaving the EU.
Eurosceptics feared that the prime minister would wait until next Tuesday’s regular cabinet meeting to lift collective responsibility, giving himself a full weekend to trumpet his renegotiation deal while sceptical cabinet colleagues would remain muzzled.
The decision reflects a growing confidence in London that the summit will produce an agreement, although foreign secretary Philip Hammond said he expected negotiations to continue "to the wire".
Mr Cameron was in Paris yesterday evening for talks with French president François Hollande and will be in Brussels today to meet the leaders of some groups in the European Parliament.
The prime minister cancelled a plan to attend a meeting of the parliament's Council of Presidents, where the leaders of all groups can attend, to avoid meeting Ukip's Nigel Farage and the Front National's Marine Le Pen.
Mr Farage said Mr Cameron had “run away scared” but the prime minister’s purpose is to secure the support of the parliament’s bigger groups for his deal, parts of which may need the approval of MEPs.
European Council president Donald Tusk is embarking on a frantic round of meetings in advance of Thursday's summit, focusing especially on central and eastern European member states.
Those governments are seeking assurances that, if Britain wins the right to impose temporary restrictions on welfare payments for EU migrants, other EU governments might follow suit.
One proposal under consideration is to allow only those countries that did not exercise their option to delay giving full free movement rights to citizens of the newer member states would be allowed to impose restrictions.
Only three countries fall into that category: Britain, Ireland and Sweden.
EU leaders are due to start discussing the British renegotiation at the start of the summit on Thursday afternoon, continuing over dinner. If the deal is agreed, Mr Cameron is expected to name the date of the referendum on Friday, with June 23rd the most likely date.
Although opinion polls suggest that the referendum is too close to call, with some showing the Leave side ahead, those who want to remain in the EU have a number of advantages. Chief among these is likely to be the central role in the campaign of Mr Cameron himself, with polls consistently showing that he can sway many wavering voters.
If no major Conservative politicians, such as London mayor Boris Johnson or justice secretary Michael Gove, join the Leave campaign, the Eurosceptics will struggle to find a leader capable of winning votes in the middle.
There are two major Leave campaigns, Vote Leave and leave.eu, which have been feuding since their foundation and show no sign of being able to come together.
