This morning, The Independent and The Guardian as well as The Times, Daily Telegraph and Daily Mail give front page space to reports that Labour MPs are calling for their leader to quit, and that Yvette Cooper and Andy Burnham are negotiating about the leadership should he do so. (Notably, both shadow ministers’ camps have this morning denied such negotiations – leaving open the possibility that they are instead just fighting like rats in a sack about the succession).

Of course, none of this would be happening if Miliband was any good at his job. If the Tory Twitter grassroots have a favourite hashtag, it’s probably #SaveEd. He is Cameron’s greatest asset, helpfully blundering on every front and shedding votes to the SNP and the Greens.

As the polling shows (both over the long term and over the summer), the two main parties are currently neck and neck not because the Tory rating has improved but because Labour voters are abandoning the Opposition with grim inevitability.

So it’s true that, as The Sun Says today, “Ed Miliband’s leadership crisis is a worrying time. For David Cameron.”

I don’t agree with The Sun‘s follow-up claim that “almost anyone else — bar Harriet Harman or Ed Balls, obviously — could put the Tories under even more pressure than they are.”

Cooper, Jim Murphy or perhaps even Chuka Umunna could potentially cause us trouble, but Burnham’s North West camp are deluded if they really believe their man could overcome all his baggage – not least Mid Staffs – to pose as a credible Prime Minister.

That aside, it is certainly true that there are several potential Labour leaders who might be able to draw back a few of those lost percentage points. And a few might well be enough, given the gross unfairness of the current boundaries, to deliver the victory hoped for in the old 35 per cent strategy.

If the bad news is that Miliband is in trouble, the good news is that it’s incredibly difficult for his rivals to get rid of him. While the Conservatives string a sword of Damocles above their leader’s head in the form of the constant threat of sufficient letters going to the ’22 chairman, at least the sword falls quickly when the thread snaps. By contrast, the Labour constitution effectively demands an assassination which must be messy, lengthy and public – more like the murder of Julius Caesar.

A Labour leader’s departure takes months or even years of open criticism, resignations to rock the boat and machinations behind the scenes. In the case of Blair, it lasted for a long time and caused the party immense internal and electoral harm. In the case of Brown, it caused just such damage but failed to get rid of him before the General Election. Given the time frame, Miliband seems much more likely to follow in Brown’s furious footsteps and hang on until May.

All of which is extremely welcome in Downing Street. If there’s one thing better for a Government than a useless Opposition leader, it’s a useless Opposition leader whose colleagues are trying but failing to get rid of him. That way, Labour will squander their time and effort on in-fighting, Miliband will be further imbalanced by paranoia and – incredibly, given where he starts from – he will suffer a further loss of authority.

As I argued on Sunday, that mustn’t be a excuse to sit back and expect to coast to victory-by-default. The imbalances in the electoral system, our reputational problems and the UKIP challenge still make this a difficult fight for the Conservatives – and even if they didn’t, we would still have a responsibility both to the nation and our party’s future to put forward a positive case for voting Tory. The longer Miliband lasts, the weaker he will become. We should leave him to wrestle with his own side, and use the time and resources freed up to make our own pitch to the people.