The north Queensland city of Townsville will be "ground zero" for the Palaszczuk Labor government as it attempts to win a third term in office on October 31.

With Premier Annastacia Palaszczuk and Opposition leader Deb Frecklington campaigning in north Queensland on Thursday, the three key marginal seats in the north Queensland capital – Townsville (0.38 per cent margin), Mundingburra (1.13 per cent) and Thuringowa (4.15 per cent) – which will shape the outcome of the 2020 election.