The scope of consolidation is based on the concept of control.
A parent company controls another company when it has control over the body which makes the financial, operating and business decisions (the decision making body) of that other company.
There are no specific rules about the effect of potential voting power or whether the decision maker is a principal or an agent when judging the existence of control.
On the other hand, similar to 'de facto control' in IFRS10, even if less than half of the voting rights are held, there are rules that require an entity to make the judgment as to whether control exists by also including the voting rights held by closely related parties or parties with the same intention after considering the structure of the Boards of Directors, the financial position, and the existence of any contracts which control policy making ability etc. of such parties.