National says it is yet to pinpoint the donation at the centre of the Jami-Lee Ross saga.

The former Botany MP is expected to go to police today, with what he maintains is evidence of Simon Bridges' alleged donation fraud.

Ross claims he was asked to help hide a $100,000 donation from an Auckland businessman.

Massey University law expert Chris Gallavin told Mike Hosking tracking the donation should be easy.

"Both the Police and National should be able to provide answers relatively quickly."

LISTEN ABOVE AS CHRIS GALLAVIN SPEAKS TO MIKE HOSKING