The moment of decision is approaching. Gordon Brown must decide soon whether he intends to call a general election this autumn.
I am not convinced he will, but he might. The odds have narrowed over the summer. One Brown ally who is pressing him to go early puts the chances at 50-50.
Some people think Mr Brown is just winding up the Tories, forcing them to disclose their hand so that he can filch some of their ideas. That might have been true once, but it has gone beyond that now. A snap election is a real possibility and Mr Brown has begun to weigh up the pros and cons in the past week.
By nature, he is a cautious man. He would not lightly risk throwing away the prize he has waited so long to collect. But he wants his own mandate as soon as he can win one. That points to an election either this October or next May.
Politicians of all hues deny being obsessed with opinion polls but they are following them now more closely than ever. Yet it is wrong to say the Prime Minister's decision will be based solely on the polls, which currently suggest a big Labour majority. There are many other factors.
Labour is £20m in the red but its once-perilous financial position is no longer a barrier to an early poll, according to party officials. The Tories could probably outspend Labour in an election next month but they might well do that anyway next year.
Staffing up for an election would be difficult for Labour, which shed more than 100 jobs after big donations dried up in the wake of the "cash for honours" affair. But the problem is not insuperable and sympathisers can be hired on short-term contracts. Mr Brown has told Labour headquarters to be ready for all eventualities. The message back from HQ is that the party machine, however creaky, can be cranked up if Mr Brown presses the button.
If the state of the Conservative Party were the only criterion, Mr Brown would definitely go now. Labour's focus groups suggest David Cameron is no longer much of an asset for his party. Voters might agree with what he says about social breakdown, especially after the terrible events in Liverpool, but many now seem to think he will "say anything" to get elected.
Although the Tory leader says he would relish an autumn election, he is hardly going to give media interviews saying he doesn't want one. To me, the Tories don't look ready. Their wholesale policy review was geared to a timetable of an election in 2008 or 2009, not 2007.
An early election would not give Mr Cameron much time to spell out what his party stands for. Even some Tory politicians are not so sure, so it's no wonder that many voters don't know.
So why give the Tories another seven months to get their act together? It must be tempting for Mr Brown to deny them the chance to turn the polls round. The political landscape might look very different next May. "Events" normally damage a government more than an opposition. Mr Brown would never admit the economy might turn down, but recent events in America show that things are not under his control.
Other issues point to a delayed election. Mr Brown would like the public to see that our troops are withdrawing from Iraq, although an immediate pull-out is not on the cards. In an autumn poll, he would have to rely on nods, winks and more "I'm not Blair" mood music. Another powerful argument for next May is that a 2p cut in the basic rate of income tax takes effect in April.
I suspect the biggest barrier to an early poll is what some Brown allies call the "why" question. In other words, how would he justify to the public holding an election only four months after becoming Prime Minister?
He could argue that he needs a mandate in his own right. But he knows that voters can punish politicians who call unnecessary elections for the wrong reasons. There is no great public clamour for a poll, no speculation in the City that risks damaging the economy.
When Labour politicians were asked why Tony Blair did not serve the "full term" he promised in 2005, they said they were elected on a manifesto for a full term. So what's changed?
Some Brownites say he could argue that the 2005 manifesto has virtually been implemented, so it is the right time to seek a mandate for a new agenda addressing the challenges facing the country.
Mr Brown frequently invokes "the national interest" when talking about Britain's relationship with America or Europe. His reputation as a strong, experienced leader – potentially a key dividing line with Mr Cameron – might suffer irreparable damage if the public judged he had called an election for selfish and narrow party interests. He might quickly become just another distrusted politician, wrecking his strategy of rebuilding the trust lost by Mr Blair.
And voters might sense bad economic news round the corner.
Unless he can answer the "why" question, Mr Brown would do better to wait. But the temptation to strike while the iron is hot is growing.