How do you solve a problem like Ukip? This is a question that has dominated Westminster this week as the party heads towards a remarkable victory in the European elections.
Much has already been said about the Tories' failed attempts to defeat Nigel Farage's party.
Cameron's offer of an in/out referendum on the UK's membership of the EU will go down as one of the biggest self-inflicted calamities in recent political history.
Instead of killing them off, Cameron's pledge inflamed ancient wounds within the Conservative party and led directly to the point where more than a third of voters now intend to vote for Ukip later this month.
If Ukip is a monster, then David Cameron is its creator. But it is not the Tories' response to the party that has most fascinated me this week. It is Labour's.
By any reasonable definition, Ukip is a racist party. Barely a day has gone by recently without some new racist, islamophobic or generally bigoted statement coming from a Ukip politician.
But it is not just the party's junior members. All parties have bad apples, although few fall so frequently off the tree as Ukip's. It is the party's most senior figures as well.
Earlier this week Ukip's deputy chairman Neil Hamilton boasted that they were now openly appealing to BNP supporters. And why not when they are led by a man like Nigel Farage? Asked whether people should be scared of Romanians moving onto their street, Farage replied simply "Well, of course, yeah."
So are Ukip a racist party? Well, of course they are, yeah. And should decent people on the left be doing everything they can to expose that fact? Well of course they should, yeah.
Yet this fact seems to have escaped many within Labour who have spent the week arguing that people should resist calling out Ukip for the racists and bigots they so obviously are.
The reason given for this is that accusations of racism do not damage Ukip and may even help them. This is ludicrous. Racist views are clearly still prevalent in the UK but only among a minority of people. The vast majority of British people are not racist and more importantly would not want to vote for a party who are perceived as racist.
It is because of this that openly racist parties like the BNP have never elected more than a handful of councillors, MEPs and assembly members in the UK. As Jeremy Clarkson discovered this week, the occasional racist joke about lazy Mexicans may be tolerated, but openly racist language is not. If Ukip can be defined as a racist party then their hopes of entering the political mainstream are over, whatever the result of the European elections.
So when Ukip bring out posters that use racist stereotypes about foreigners stealing our jobs, Labour should stand up against them. And they should do so for both political and for principled reasons.
This seems obvious, which suggests to me that there may be a far more cynical belief propelling the Ukip apologists in Labour.
So what could it be? Could it be a fear of doing anything that might burst the Ukip bubble currently lifting Ed Miliband into Downing Street?
I sincerely hope not, because that way lies danger, not just for Labour, but for the rest of the country as well.