And those on his side of the political divide have clearly seen the Tucson tragedy as an opportunity to score points and settle scores.

None more so than with Sarah Palin, a politician who is almost as divisive as the President. The former Republican vice-presidential contender has become a spiritual figurehead for many Tea Party supporters, but is loathed by many on the Left.

So it was that within minutes of the Tucson shooting, anti-Palin internet bloggers and Twitter users were highlighting a so-called ‘target map’ Mrs Palin had posted on her Facebook page last March…

But those lessons from ­history won’t stop some Democrats exploiting the shooting of a nine-year-old girl and five others at the weekend with precisely the sort of foam-flecked over-reaction for which they love to condemn their opponents on the Right.