While some in his Conservative Party may relish the prospect of an early referendum on Britain’s European Union membership, Prime Minister David Cameron should postpone it for as long as he can, argues Janan Ganesh.

The Financial Times columnist cautions Cameron and his team against seeing the referendum as a “chore to get out of the way, as if the following morning will bring new vigor and a world of possibilities.” They overestimate the loyalty of Conservatives, he believes, who — whatever the outcome of the referendum — will start preparing for the post-Cameron era the day after the vote.

Before May’s election, when the Conservatives won their first absolute majority in two decades, Cameron said he wouldn’t stand for a third term. He is unlikely to burden his party with a leadership contest close the 2020 election, so a resignation is expected somewhere around 2018.

If Cameron fails to persuade Britons to vote in favor of continued European Union membership in the referendum, his premiership would become untenable.

But even if, as polls suggest, a majority votes to stay in once Cameron has negotiated some changes in the country’s relations with the rest of the bloc, the end of his tenure will close in as well, according to Ganesh.

Tory outers will not forgive his part in eliciting the wrong answer from the British public. Everyone else will sense that the point of his premiership has expired.

Putative successors, like London mayor Boris Johnson and Cameron’s deputy and chancellor, George Osborne, will have to start positioning themselves as future leaders.

So the talk of staging the referendum next summer is “bizarre,” writes Ganesh. “Why forfeit eighteen months of government?”

Cameron has plenty to do. He won a strong mandate in May for continuing to shrink the state, reduce the number of Britons on welfare, free schools from central planning, devolve powers to England’s major cities and raise employment and wages in the private sector. This program is far from complete and could be partially reversed under a more reactionary successor — or a Labour government. By calling a referendum next year, Cameron could deny himself the opportunity to see his reforms through.