CFMEU boss Zach Smith, one of the construction union’s few remaining elected leaders, has suggested a controversial decision by the union administrator was behind his surprise decision to step down from his national leadership role.

Smith, who is the CFMEU national secretary and the administration’s appointed head of the Victorian branch, told staff on Thursday he had made the “tough” decision to step back from the national position as “I cannot do justice to both roles” and Victorian members “deserve my full focus”.