The message, brutal in its simplicity, provides a sardonic measure of the task the NP faces if Mr de Klerk is to succeed in his stated objective of securing a significant proportion of the black vote in the coming all-race elections.
On the advice of (among others) Sir Tim Bell - the professional British image-maker who is being paid to do for Mr de Klerk what he did for Margaret Thatcher - the NP has hit upon the device of projecting itself as more African than the ANC.
Thus, on an election stop in a rural village last weekend, Mr de Klerk did what Nelson Mandela has yet to do on the campaign trail and, courtesy of a local chieftain with either a very good or a very bad sense of humour, sheepishly donned traditional African tribal dress.
At the party's national congress, which started on Wednesday and ended yesterday, the white delegates were almost outnumbered by those with dark skins. The congress chairman was a black former member of the ultra-radical Pan-Africanist Congress, and the church minister who led the opening prayer was from Soweto.
The party was trying hard not to be white and the spectacle should have been heart-warming. But the note failed to ring true.
Perhaps it was the speech of the black minister praising Mr de Klerk as a visionary, as the man who liberated black South Africa, who freed the ANC prisoners from the jails. Perhaps it was Mr de Klerk himself confidently urging his audience to ponder the question, 'which of the two main parties - the National Party or the ANC - has dirty hands?' Or perhaps it was the assembled 'new Nats' ' rendition of black South Africa's traditional anthem of liberation, 'Nkosi Sikelele i'Africa' ('God bless Africa').
In Katlehong township, 24 hours earlier, a crowd of around 1,000 ANC supporters who spontaneously gathered to see Mr Mandela had bellowed out the song's melancholy cadences with the jubilation of a crowd whose team has just won a cup final. At the NP rally, however, both the white and black sectors of the audience seemed at an embarrassed loss, most of them lip-reading the words from a big screen.
Why were the blacks there? A number, judging from the zeal with which they aped the ANC liturgy with their 'Viva de Klerk', had evidently undergone a genuine conversions. Others, it was hard to avoid the conclusion, were there for the food and beer.
On Sunday a smiling Mr Mandela had told a crowd of his supporters: 'If the National Party offers you stew, potatoes and an orange to go to the rally, I say go. And then vote for the ANC.'
Some people have already taken Mr Mandela's advice and, no doubt, many more plan to: proof, after all, that there is such a thing as a free lunch.