GETTY Boris Johnson and Michael Gove have both been wavering over whether to vote for Brexit

FREE now and never miss the top politics stories again. SUBSCRIBE Invalid email Sign up fornow and never miss the top politics stories again. We will use your email address only for sending you newsletters. Please see our Privacy Notice for details of your data protection rights.

David Cameron's promise not to rig the EU referendum by forcing Eurosceptic ministers to back Brussels appears to have unravelled after the double hit on the Prime Minister’s inner circle. Mr Gove reportedly wants to back the 'leave' campaign, but is holding back from doing so because he is worried about the Prime Minister's response.

It adds to fears few ministers will be prepared to put their country's interests above their own political ambitions. The revelations made a mockery of Mr Cameron's hollow plea in parliament yesterday for MPs to "follow their heart" on Europe amid criticism the referendum campaign is already being swayed in favour of staying in the EU.

GETTY Boris Johnson will be offered a plum Cabinet job to ensure his support for Brussels

GETTY Mr Gove is said to be torn between his conscience and his loyalty to the Prime Minister

Mr Gove - a long-time ally of Mr Cameron - would be a big coup if he came out in favour of Brexit and would almost certainly be asked to lead the campaign to sever ties with Brussels. But friends say he is torn between his personal loyalty to the Prime Minister, who sacked him from his post as Education Secretary in July 2014, and his belief that Britain would be better off outside the EU. Friends of Mr Gove said he is "intellectually convinced" of the case for leaving the 28-nation bloc. He is also said to be deeply uncomfortable about Mr Cameron's demands that he front plans for a new constitutional court in Britain, to override EU directives, which he privately believes is unworkable.

Without Boris the Leave campaign does not have a leader Pro-EU source

However, in a glimpse of the back-door political wrangling which will shape the direction of the referendum campaign, Mr Gove is believed to be worried about contributing to a campaign which could wreck the Prime Minister's legacy. Mr Gove's spokesman said the minister would not decide until a deal is struck, insisting: "Like the prime minister, he has not ruled anything out." The revelations come after it emerged Mayor of London Boris Johnson has been offered a "top Cabinet job" to ensure his support for remaining in the EU. Mr Cameron had been worried that the Tory heavyweight who reacted with disdain to yesterday's draft agreement on Brussels reforms, could break ranks to front the leave campaign.

GETTY EU chief Jean-Claude Juncker hailed Mr Cameron's EU deal

GETTY The Prime Minister has been accused of trying to corral Ministers into voting for Brussels

But a source in the pro-Brussels camp has now revealed Mr Johnson has promised a senior position in the Cabinet once he finishes his second term as London Mayor on May 5. They said: “The one person who could galvanise the Out campaign would be Boris: he’s the one we really fear. “Without Boris the Leave campaign does not have a leader.”