TVNZ's multi-party debate this week illustrated key features of this election campaign: the minor parties' rising popularity, and the complicated role of NZ First.  With polls they would need Winston Peters, National and ACT have been continuing to talk down his appeal - but it remains preferable to defeat.  In Focus on Politics this week, RNZ deputy political editor Craig McCulloch dissects the past week, speaking to Guyon Espiner alongside RNZ and NBR political editors Jane Patterson and Brent Edwards, and RNZ political reporter Anneke Smith.