Conservative Victorian Liberal powerbroker Marcus Bastiaan is set to quit the party’s key decision-making body, citing the illness of a family member as the reason for standing down.

In a surprise announcement, Mr Bastiaan confirmed he and his wife Stephanie, also a conservative Liberal activist, had both stepped back from their party activities.

Mr Bastiaan, 28, has been credited with driving the party to the conservative right by rigorously recruiting new members from organisations such as Mormon churches.

He is an ally of party president Michael Kroger and their faction now dominates administrative committee giving them a huge influence over the party’s direction.