Standing outside No 10 Downing Street yesterday, his wife Samantha to the side in the company of officials, David Cameron laid down in just 14 words the pledge that will consume thousands of hours in the next two years.
Looking tired but pleased to be back in Downing Street, if more than a little surprised to be so with a parliamentary majority, Cameron declared simply: "And yes, we will deliver that in/out referendum on our future in Europe. "
It was a pledge that he did not want to make, even if he now makes a virtue of it. He must now deliver an agreement with 27 European Union states that can win the approval of Eurosceptic backbenchers and, ultimately, that of the British public.
From the vantage point of today, it seems, at best, that he can meet two of those criteria, if that. He risks not getting a deal at all; or getting one that cannot win the approval of his backbenchers.
Or he risks getting a deal that will include concessions on welfare and other limited issues that do not require EU treaty changes, but one that can only win the approval of voters with the help of other parties because his own party splits.
The Conservatives have form, even if one has to delve back into history, evoking memories of the fracture that took place within it over opposition to the abolition of the Corn Laws in the 19th century – an outcome that kept the party out of power for decades.
Rebellions
In the 1990s, John Major’s administration was convulsed by opposition from within his ranks to the Maastricht Treaty, which created a poison that eventually helped to ensure the Conservatives were swept out of power by
Tony Blair
in 1997.
If anything, the House of Commons is more rebellious now. There were a total of 50 backbench rebellions by coalition MPs, mostly Conservatives, in the months before the Commons rose in March: that is 50 rebellions out of 188 votes.
Given the difficulties he could face, Cameron may be tempted to reach some form of accommodation with the Democratic Unionist Party to give him some comfort on some tight votes, though the DUP tends to be as Eurosceptic as some of his own.
For now, the negotiating bar remains set high. In his Bloomberg speech in 2013, Cameron called for a “new [EU] settlement” based on five principles: competition, flexibility, power flowing back to member states, democratic accountability and fairness.
However, he argued that the EU should abandon the commitment to “ever-closer union” included in its founding treaty – a concept anathema to most capitals; while he wanted to limit the impact, too, of the Council of Europe’s Court of Human Rights on British law.
If that could not be agreed, then he would seek an individual deal for the United Kingdom, one that would involve "a relationship with the single market at its heart", and would offer British voters a simple choice.
The speech had been designed to quell his rebellious ranks but the sedative did not last long. By late last year, he was forced to return to the subject, heightening speculation that he was going to demand curbs on the EU’s free movement of people rules.
Given private warnings from Berlin and elsewhere that such measures would not be countenanced, Cameron backed off. Instead, he demanded that EU migrants should have to wait for four years to claim benefits.
Child benefits should not be paid for children who were not living in the country where their parent worked; EU migrants should be forcibly removed after six months if they had not found work, he said.
And he produced a flurry of ideas designed to win favourable Daily Mail coverage, in which he insisted that EU states should be able to speed up deportations of convicted criminals, along with longer re-entry bans on beggars and fraudsters.
Then, however, he did make one key concession to his Eurosceptic ranks, by declaring that he would “rule nothing out” if the UK’s demands fell on “deaf ears”, the strongest hint so far that he might be prepared to recommend a No vote.
In the wake of yesterday’s result, Cameron is hoping that his negotiating hand with other EU states has been strengthened, though his hopes for a 2017 deal are difficult to see happening, while there is far less chance that anything could happen more quickly.
Irritated
Few of his fellow EU leaders trust him. Too often, he has been seen to tack and weave for short-term political advantage, seemingly oblivious to the problems that he creates. German chancellor
Angela Merkel
was initially well disposed towards him but quickly became irritated.
The absence of the Liberal Democrats in government will also concern other EU capitals – most particularly Dublin; but it may pose problems for Cameron himself too, since the Lib Dems were a useful tool on occasions to blame for perceived government failings.
Following the drubbing it has received, the Labour Party will have to withdraw and lick its wounds, but also review its priorities, though, so far, there is nothing to indicate that the next leader will have different thoughts on the EU to Ed Miliband.
Miliband took a very determined line, refusing to heed demands from within his own ranks, from people who were concerned about being outflanked by the UK Independence Party, that he should match Cameron’s pledge to hold a referendum on EU membership.
Though Ukip was bloodied in the election; it garnered nearly four million votes, which gives it a reach across parts of the north of England that it has never had up until now.
Its leader, Nigel Farage, quickly announced his resignation; though on closer examination it looked more like a long summer holiday, since he added that he may put his name back in the ring for the leadership in September.
In the months ahead, there may be occasions when Cameron, sitting in the cabinet room surrounded by his red boxes, may wish that he still had Nick Clegg’s mobile on speed-dial.