Shadow foreign secretary William Hague, shadow chancellor George Osborne and shadow health secretary Andrew Lansley are among those remaining in their current posts.
On Tuesday, Chancellor George Osborne, Foreign Secretary William Hague and Home Secretary Theresa May wrote to the Daily Telegraph in an attempt to persuade Tory MPs to back the plan.
None of their top four Mr Cameron, George Osborne, the shadow chancellor, William Hague, the shadow foreign secretary, and David Davis, the shadow home secretary is outclassed by his Labour opposite number.