By Nick Assinder
Political Correspondent, BBC News website
Conservative leader David Cameron's description of UKIP as a bunch of "fruitcakes, loonies and closet racists" seems to have done the trick.
Mr Cameron: UKIP are "fruitcakes, loonies and closet racists, mostly"
It has got him on the news bulletins (result no 1) for suggesting his Tory party has absolutely nothing in common with the party which once boasted Robert Kilroy Silk and Joan Collins among its members (result no 2).
And, as such, it can be seen as part of his campaign to distance the all-new Conservative Party from anything that smacks of extremism, illiberalism or, well, nastiness.
The remark echoes his predecessor, Michael Howard's description of UKIP party members as "cranks and gadflies" .
All good, not-so-clean fun that even UKIP is happy to accept with a smile.
But has Mr Cameron gone too far by suggesting some UKIP members are "closet racists"?
That charge is easily levelled but not so easily sustained and has, in the past, led to difficult court cases.
It is also one of those labels that, once applied to an individual or group, may well stick - as any former PR man like Mr Cameron will fully understand.
And it is that "racism" tag - something UKIP has faced before - that has so angered the party and led to demands for an apology under the threat of legal action.
Farage has demanded an apology
Their leader in the European Parliament, Nigel Farage, seems happy to put up with being branded a fruitcake, loony, or gadfly - to the extent of having special gadfly ties created for party members.
But charges of racism are of a different order and cannot, he insists, be brushed aside with a smile like the other insults.
He says UKIP are a non-racist, non-sectarian party who "will not accept this type of smear being used... Mr Cameron needs to learn that this sort of language in the 21st Century is simply unacceptable".
He is also seeking to turn the tables by suggesting the attack suggests UKIP have got the Tories worried.
He points out - and it is something Mr Cameron certainly has not forgotten - that UKIP scored a significant advance in the 2004 European elections, winning a dozen seats in Brussels, and 2.7m votes, often at the expense of the Tories.
Its local election campaign launch last week saw the party stressing its plan to target any traditional Tory voters who may feel Mr Cameron, in moving the party towards the centre-ground, has moved it away from them.
And, so long as attacks like this are made on UKIP, it is difficult to also claim they are irrelevant.