Ukip leader Nigel Farage has repeatedly challenged the Prime Minister to a televised debate.
His most recent call to face Cameron on air came last week in response to claims he was "chicken" for ruling out a run at Parliament in the Newark by-election.
The Ukip leader said: "Mr Cameron said ... that I was a chicken. Well, I'll tell you what Dave, why don't you come on telly and do a debate with me?"
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Another cold, frosty and foggy night for many. Northern and western areas will see thickening cloud, patchy rain and milder temperatures.
Temperatures have already plunged to -12C in some parts of the UK this winter - but Thursday could be the coldest day yet.