Former treasurer Mike Nahan has been voted in as leader of the Liberal party with Liza Harvey the deputy leader.

Dr Nahan was elected unopposed in a Liberal party room meeting after former Premier Colin Barnett stepped down as leader and moved to the backbench.

Dr Nahan says he wants to be the Liberal leader for the long term and lead the party back to Government after the landslide state election loss.

He spoke with Oliver Peterson.