By John Pienaar
BBC Radio 5 Live chief political correspondent
They tell jokes about Gordon Brown these days on Strictly Come Dancing.
Vince Cable had opposition MPs in stitches
Jokes so bad they are hilarious.
But none of them come close to Vince Cable's killer one-liner in the Commons this week.
The prime minister had been transformed, he said, from "Stalin into Mr Bean."
The PM's face fell.
Opposition MPs fell about.
Quite a few Labour members struggled not to do the same.
The truly worrying thing, from the Brownite perspective is that, just now, a man who's worked hard to establish strength, sound judgement and deadly seriousness as his defining characteristics seems to be in danger of becoming a figure of fun.
Tony Blair was generally despised or admired.
Margaret Thatcher was often both, at once.
I cannot remember an exquisitely delivered one-liner hitting home against either of them in quite the same way as we saw this week (though, where Mrs T was concerned, Denis Healey came close a few times).
Labour MPs insist the government's position is recoverable, despite the latest wave of grim opinion poll results.
That must surely be true.
Not even the most optimistic Conservative MP seems to believe the government has reached the kind of tipping point their party experienced on Black Wednesday, in 1992.
Even then, the Conservatives continued, miserably, in office for five more years.
The worst run of bad luck must end at some point. Mustn't it?
And arguably, dumb, dreadful luck is the only thing that explains such a run of political catastrophes in such a small space of time.
'Get a grip'
Incompetence in the government machine played a distinguished part, obviously.
But the recent run of events also suggests strongly that the prime minister has, at some stage in his career, offended a witch.
Add to that, the established fact that, once a reputation for all-round uselessness sets in, anything that goes wrong tends to reinforce it.
Labour MPs are now heard muttering about the need for the PM to "get a grip" - ironic since he has been forced to work hard to dispel his reputation for control freakery.
The spectacle of Harriet Harman's people implicating Gordon Brown's more deeply in the funding row - and the flurry of claims and counter claims that followed - conjured an impression much closer to freakery than control.
Meanwhile, the notion that too much power and influence is still contained to narrowly within a tiny inner corps of trusted friends and Brownite advisers is gathering force.
Some on the Labour side say they will be a happier when they see more evidence the "inner circle" has been allowed to expand, at least a little.
Sooner or later, Mr Brown's supporters believe, he will get his chance to be judged more on his own terms.
Then, he might be able to set out the "vision" they say is needed to re-inspire the faithful.
Assuming, that is, Labour's luck changes.
And assuming the laughter dies down.
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