What about the pro-European Conservatives?
Where have all the pro-European Conservatives gone?
True, the odd big beast like Ken Clarke is still roaming around the parliamentary reservation savaging the occasional Eurosceptic straggler he might come across.
In characteristically robust fashion he took to the airwaves earlier to lambast some of his colleagues who "should obviously be in UKIP" and were pandering to "a wave of hysteria" over immigration. Ouch.
But by and large the pro-Europeans seem an unduly meek and cautious bunch, almost mole-like in their reluctance to come blinking into the daylight.
A far cry from their raucous, self-confident Eurosceptic colleagues, many of whom only have to see a camera to be rushing in front of it.
Which is not to say the pro-European Tories have gone away. Far from it. Most are biding their time. And many of them are as mad as hell at what they see as their party's remorseless drift towards UKIP.
One former pro-European minister noting the relentless pressure on the PM from Eurosceptic Tories observed, only half in jest: "The only thing that would satisfy them is bombing Berlin."
But they have a much more serious concerns than simply trading abuse with the sceptics.
Their fear is that the Conservative Party is being steadily dragged away from the centre ground, the ground on which they argue elections are always won and which David Cameron occupied at the last election.
They also point to the experience of the recent Newark by-election where the Tories - temporarily - halted Nigel Farage's bandwagon by appealing to disaffected Liberal Democrat and Labour voters rather than chasing the UKIP vote.
As one exasperated pro-European minister noted: "Why on earth should anyone bother voting for a pretend UKIP party when they could vote for the real thing?"
The prime minister, they insist, has a good story to tell on the economy, so why is he allowing himself to get sucked into a row about Europe? After all wasn't he the leader who said the party had to stop "banging on about Europe"?
Which begs the question: Why don't the pro-Europeans go public with their concerns? Why don't they take on the sceptics?
Here the pro-Europeans tend to shuffle, look at the ground and become more muted.
Their concern is this. Any public fightback, they fear, would tear the party in two. And divided parties, they argue, do not win elections.
Instead their hopes appear to centre on the Mr Cameron's instincts. They believe, at the end of the day, he accepts that Britain's national self interest is in remaining in the EU.
The Rochester by-election, they say, is a one-off. Mr Cameron has no option but to throw the Eurosceptic kitchen sink at it in order to win.
But afterwards they hope there will be an end to the appeasing of the sceptics.
And if there isn't?
Well, perhaps some of them will have to start taking some lessons from an old bruiser like Ken Clarke.