Image copyright AFP Image caption Mitt Romney's describes why he cannot go after Mr Obama in a personal way

For days now conservative bloggers have been fulminating that Mitt Romney doesn't get a fair deal, that the media doesn't give him a chance, and is out to get him.

Their protests are likely to get louder as Mother Jones, which describes its mission as fighting "an out of control right-wing lie machine", releases a video of a Romney speech to a private audience of big donors.

He actually sounds a lot more politically savvy than he does on the stump. His explanation of why he can't attack Mr Obama full-throttle is particularly interesting.

I argued after the Republican convention that if it appeared flat, it was because it had to be: ramping things up would have put voters off. It is nice to hear the same point from Mr Romney's own mouth.

He tells the wealthy donors that it is all about those critical 10% in the middle, that "because they voted for him, they don't want to be told that they were wrong, that he's a bad guy, that he did bad things, that he's corrupt".

But it is his scornful take on Obama voters that has really grabbed the headlines.

He says the majority of them can't be peeled off because they pay no income tax. He says these voters are those "who are dependent upon government, who believe that they are victims, who believe the government has a responsibility to care for them".

What is particularly interesting is the figure he puts on this - 47%. It struck me on first reading as remarkably high.

Are nearly half of voters in a country known for its relative lack of welfare provisions really welfare dependents?

This article, by the Washington Post's Ezra Klein, does show that 46% of US households don't pay income tax. Meanwhile, 61% of those who pay no federal income tax do pay payroll tax at 15.3%.

Another 22% of the non-income tax-payers are elderly, according to the Ezra Klein article. If that is correct, 83% of those who do not pay income tax don't really fit Mr Romney's characterisation, except in so far as his argument is that people who don't pay income tax aren't impressed by promises of income tax cuts.

There's little doubt this video was released with the desire to hurt Mr Romney, and that will lead some to cry foul.

But elections are a rough game and he is left looking snooty towards half of America - it reinforces the very image of him the Obama campaign are trying to push.

How soon will they produce T-shirts with "I'm one of the 47%" on them?