Mongrel and maths collide as campaigns launch - and media ponder National's tax plan; scrutiny of candidates' online footprints prompts pushback and claims of 'agendas'.

Mediawatch looks at how the media handled the biggest opposition policy announcement so far in the election campaign - the National Party's proposals on tax.

Also: increased scrutiny of some of the candidates for a seat in Parliament - which also sparked a backlash against the media.

Go to this episode on rnz.co.nz for more details