The Federal Government has been rocked by revelations Deputy Prime Minister Barnaby Joyce may not have been validly elected. Barnaby Joyce is the latest to be caught by uncertainty over his citizenship - telling Parliament he may be a dual citizen of New Zealand because his father was born there. Mr Joyce is staying on as Deputy PM while the High Court determines his eligibility, but the Opposition believes he should stand aside immediately. The case could have huge implications for the Coalition, which holds the Lower House with a slim one seat majority.