he PM woke up to four identical letters from Ed Miliband, Nick Clegg and Nigel Farage this morning. It would be "unacceptable" if the interests of "one party leader" meant that the debates were mothballed (you can read a full copy of the letter here, and Matt Holehouse's story is here). They've also agreed to take place in the debates even if Mr Cameron gives the whole thing a pass, raising the prospect of the PM being represented by an empty chair.
That sanction looks unlikely to happen. As Nick Robinson pointed out on the Today programme, the 4-3-2 format proposed by the broadcasters (Messrs Cameron, Clegg, Farage and Miliband in one, Cameron, Clegg and Miliband in another and PMQs Extreme in the third) means that whoever gets the previously golden ticket of the big two will be left with an hour long monologue by Mr Miliband.
As you'd expect, privately the PM's opponents are fuming at what they see as his cowardly behaviour. It may be more of a problem that 55% of the public agree with them, at least according to the latest ComRes poll for ITV News. (Just 23% disagree, while, a YouGov poll for the Times finds that 70% want the debates to go ahead.)
That said, arguments over the debates are unlikely to move the dial one way or the other. As today's Guardian splash on the Conservatives' continuing lack of trust on matters relating to the Health Service illustrates, that party has rather bigger electoral problems than a row that will blow over in a day or two.
Forget the prospect of Mr Farage lobbing grenades from outside in that four-way debate, as bad as that would be. The real danger is that two-way clash with the Labour leader. Downing Street, like most of Westminster, believes that Mr Miliband will outperform expectations in the debates, and even having the Labour leader on a podium alone with the PM elevates him to a level that the Tory campaign would prefer he remained comfortably below.
But I just wonder. These bubble rows do occasionally leave a larger mark. Labour organisers still face a barracking over the selling of the gold on the doorstep. (It's behind only Iraq, immigration and the leadership according to two I spoke to recently) In that case, Gordon Brown's sell-off lingers because it feeds into the perception that Labour spent like drunks in a casino. It may be that shirking a fight for party-political reasons confirms wider fears about the PM at the worst possible time. Perhaps signing up to that Telegraph-Guardian debate on YouTube wouldn't be such a bad idea.
COST OF LIVING CRISIS...IN CRISIS
Supermarket price wars and the fall in the global oil price have brought inflation down to 0.5%. "Low prices are here to stay, says Osborne" is our splash. "It's good news for everybody," the Sun roars in its leader, "Except Red Ed." It contributed to a chipper mood at David Cameron and George Osborne's meeting with the parliamentary party. It's 1992 all over again, the Chancellor told MPs. But as James Kirkup explains, it isn't all good news.
THE ICEMAN...MAY BE SOMEWHAT DELAYED
Labour may be forced to rebrand their energy price freeze as a price cap, Kevin Schofield reports in the Sun. If energy prices continue their slump then a freeze could have the perverse effect of making prices higher. Labour insist that the policy was always a cap, not a freeze.
SHE SNOOPS TO CONQUER
The security services must be given more powers to monitor communications to counter the sense of "vulnerability and fear" that people feel in the wake of the murders of Jewish supermarket shoppers and the attacks on Charlie Hebdo magazine, the former head of M15, Baron Evans, warned the Lords in his maiden speech. David Cameron will make the passage of a revived "Snoopers' Charter" a red line in coalition negotiations with Nick Clegg, senior government sources tell Peter Dominiczak and Chris Hope.
THIS CHARMING MAN
There are areas of French cities that are "no-go-zones" for non-Muslims and even the police, Nigel Farage told Fox News. The "police and all the normal agents of the law have withdrawn" from certain areas "wherever you look", he added. "It isn't just France. It is happening right across Europe."
Conservative spending plans will lead to "Dickensian" public services, Danny Alexander says. George Osborne's plans would "hit millions of families trying to make a success of their lives", Mr Alexander wailed. Patrick Wintour has the story in the Guardian.
MAN CANNOT SLIM BY BREAD ALONE
David Cameron has stopped eating bread in order to lose a few festive pounds. "I'm giving up bread," the PM told BBC Radio Sussex, "It worked before, maybe it will work again, who knows?" "It is a great patriotic struggle,"he added. Ben Riley-Smith has the story.