Kumar told PTI about the nomination of the three national spokesmen.
Tyagi is secretary general of JD(U) in the newly constituted team of office bearers of the party announced by Kumar.
Diplomat-turned-politician Pawan Varma and journalist-politician Haribansh have been made general secretaries of the party.
Varma is the visible face of the party particularly on English TV channels. Haribansh, an acclaimed journalist in Hindi, is also Rajya Sabha member from JD(U).
Kumar had announced his new team of office bearers recently after formal ratification of his election as JD(U) national president.