An infinitely variable power branching transmission with first and second operating modes, whereof the components are distributed between two power paths connecting in parallel an engine to vehicle wheels. At least two planetary trains, two electrical machines, a reduction stage, and a control orient differently the power between the transmission input and output based on the operating mode thereof. Two reduction stages are arranged in parallel between the two planetary trains on the same power path, the two reduction stages being respectively urged in the first and in the second operating transmission mode.