Figures from the latest YouGov poll on the EU referendum will not be music to David Cameron's earsToby Melville/Reuters

Negative publicity around Prime Minister David Cameron's EU deal has handed the leave campaign significant momentum, with the latest YouGov poll pushing Leave ahead of Remain by nine points. According to figures from the latest survey, 45% of people would vote to exit the EU while 36% would choose to stay in the bloc.

The leave lead has seen an increase of four points from last week. The polls have often been close and the latest gauge in public sentiment – which is the first since details of the draft renegotiations were made public – is a blow for Cameron. Cracks have started to appear in the Tory camp, with several MPs attacking the deal as "thin gruel" and saying that the emergency brake on migrant benefits will have "no impact whatsoever". Cameron has refused to back down, saying that "hand on heart" he has achieved his manifesto commitments.

In spite of the bad reading for Cameron, YouGov notes that "all of the changes proposed within the deal are popular – aside from withdrawing from the commitment to 'ever closer union', supported by 47% to 14%." Overall, 22% of people consider Cameron's renegotiations with Tusk to be a good deal, while 46% think it is bad. Some 1,675 British adults were surveyed as part of the research undertaken for The Times.

Splits are increasingly emerging from within the Tory ranks after Eurosceptic ministers tore into the outcome of Cameron's deal. The prime minister appealed to his MPs to support him and warned against adopting "a view because of what your constituency association might say". But the plea drew condemnation, with the Campaign for Conservative Democracy chairman drawing comparisons with dictatorship.

"The essence of leadership is to listen to your followers and then take a decision," said John Stafford. "The essence of dictatorship is to tell your followers, 'this is what's going to happen'. I'm afraid Cameron has moved into the latter position of dictator. What he should always remember is that the party members are the ones that put Conservative MPs into their position. If you don't listen to them they will react."