Dr Paul’s ruthless application of his convictions - minimal government, localism, personal freedom and adherence to the letter of the US Constitution - alienates many of the conservatives who might have been expected to back him.

For example, although he doesn’t agree with abortion - as a GP, he says, he delivered thousands of babies, and never came across a case where a termination was necessary for the mother’s physical or psychological well-being - he insists that abortion law ought not to be a federal prerogative and, during his 2008 presidential bid, resolutely refused to give the Pro-Lifers the assurances they wanted.

Similarly, when almost every conservative legislator, including a great many Democrats, supported a law to prevent gun-shops being sued for crimes committed with weapons they had sold legally, he voted against the measure on grounds that it represented a usurpation of jurisdiction from the 50 states

Many Republicans regarded his opposition to the Iraq war as almost treasonable. Although the issue is no longer the shibboleth it was - plenty of conservatives, knowing what they now know, wish that they had kept the trillion dollars to spend on something else - Ron Paul is still treated with suspicion.