His public speech sought to set out a new European policy which he hopes can shut up his strongly Eurosceptic party.
One issue is the Conservative effort to define a set of issues on which they believe that it would be possible to achieve agreement with other member states - mainly in social legislation.
This is a matter of diplomatic politics - and of domestic politics, given that the impact may often be to weaken employment protections and maternity rights. Left Foot Forward has a critical analysis of these issues. The Conservative intention is to define goals that are limited and achievable. While there are some substantial employment policy issues here, it is difficult to see the proposed changes would mark a fundamental change Britain's EU membership, which currently involves being outside the Eurozone and Schengen, though Labour dropped the opt-out of the social chapter.
I think it will suit the Conservative leadership if the focus is about whether or not they should seek to achieve these goals.
But the speech included a set of other sovereignty guarantees that will need a good deal of scrutiny to find out what they amount to - and whether they amount to much at all. Here are some early questions:
1. How would a referendum lock work?
If we win the next election, we will amend the European Communities Act 1972 to prohibit, by law, the transfer of power to the EU without a referendum. And that will cover not just any future treaties like Lisbon, but any future attempt to take Britain into the euro. We will give the British people a referendum lock to which only they should hold the key – a commitment very similar to that in Ireland.
Firstly, will this mean a British EU referendum on every new accession Treaty? No new non-accession Treaties are likely for more than a decade. If Cameron excludes accession treaties from the referendum lock, then the Eurosceptics will claim they are being used to sneak in transfers of power.
Secondly, the claim to prohibit the any "transfer of power" outside of Treaties sounds very difficult to work through. This is the devil in the detail of this claim. UKIP and Conservatives such as Messrs Cash and Hannan make contested claims that new powers are being transferred every day before breakfast; certainly at every Council of Ministers meeting. Others may challenge these claims - indeed Cameron may say they are calls for "a made-up referendum".
If there are disputes of this sort, then the "referendum lock" may prove something short of a cast-iron guarantee.
2. Is the United Kingdom Sovereignty Bill anything more than symbolic?
Cameron says he will model this on the German legislation. As such, it risks merely being a symbolic statement of what is already true: the British Parliament can repeal the 1972 European Communities Act and the Lisbon Treaty contains an exit clause. Or would a new UK law have the effect of overturning the Factortame judgements, with regard to the applicability of EU law in the UK? If so, will that be compatible with UK membership.
I suspect the inclusion of the line "This is not about Westminster striking down individual items of EU legislation" is significant here to mark the boundaries of what a Sovereignty Bill will enable, but again this may well mean that Cameron's Sovereignty Bill is simply a symbolic gesture.
3. Will these proposals amount to a "fundamental renegotiation" of British membership?
Cameron will come under Eurosceptic pressure if he does not achieve what Eurosceptics demand. This was how Tim Montgomerie summarised the position on Sunday:
If Britain's relationship with the EU is fundamentally the same after five years of Conservative government the internal divisions that ended the last Tory period in government will look like a tea party in comparison.
It is difficult to see that Cameron is offering anything that even pretends to be on this scale.
[UPDATE: That is also Tim Montgomerie's view, as set out at CommentisFree, and on ConservativeHome, though Montgomerie is now pledging a "vow of silence" for several weeks on Europe, having apparently lost this round of the argument].
And though the core Eurosceptics championed him for leader, it is difficult to see how he could do so without sending Britain towards the EU exit door.
This call for a "fundamental renegotiation" is in large part a "false flag" policy by those who want to get Britain out - but do not want to call for a referendum for Britain to leave now.
There is no renegotiation of British membership of an actually existing European Union which would settle the question for the core Eurosceptics.
There may be relief in other European governments, and in the Foreign Office, if the Conservative policy was to turn out to be primarily a political one of party management. Others will argue that there would be a significant opportunity cost by focusing on a mainly symbolic set of demands, while other opportunities for influence will be lost, for example, by the Conservative Party having strained its relationships with Angela Merkel, Nicolas Sarkozy and others who could have been natural allies of a modern progressive centre-right party.
The difference between Cameron and his sceptic critics was summed up in the fascinating anecdote in The Times today, with which Daniel Finkelstein opened his column:
The first time I had lunch with David Cameron, I noticed that he was wearing something odd. He sported a pair of European Union cufflinks. It was a striking thing to do in those days, the early 1990s. The Conservative Party was rowing constantly about the EU, and he worked as a special adviser to a Eurosceptic Cabinet minister. So naturally, I asked him about them.
I don’t think European federalists should have a monopoly on being part of Europe, he replied. And in explaining his choice of cufflinks on that day many years ago, he provided an insight into the position on Europe he has held since.
[Cameron's set] are properly, robustly Eurosceptic while being completely at home with membership of the EU.
Ask Messrs Carswell, Hannan and Montgomerie this:
Have you ever worn a pair of EU cufflinks? Would you ever do so?
I would be pretty sure the answer will be no. Stressing European cultural reference points is one thing; sporting the blue and gold flag which symbolises the European Union something else entirely.
That is why Cameron's speech will not have satisfied the Eurosceptic base - and why he may now realise that he can never do so.