Rogue Victorian MP Geoff Shaw's future remains in doubt with a magistrate ruling he is not suitable for a diversion order over a charge of misusing his fuel card.

The MP will now plead not guilty to the original 24 charges, which were on Wednesday rolled into one count of obtaining financial advantage through deception in the Melbourne Magistrates Court.

Geoff Shaw leaves court after Thursday's hearing.

The unexpected ruling means the Napthine government still hangs by a thread, with next year's court ruling likely to decide if a critical by-election is held in Frankston. A guilty finding would force Mr Shaw from parliament.

Magistrate Charlie Rozencwajg said an option to deal with Mr Shaw's charge through a diversion program was "not appropriate" but did not say why. Mr Shaw has been ordered to re-appear in court on February 17 to contest the charge.