New Zealand's ambiguous election outcome could trigger a wave of senior executive departures from leading Kiwi banks before the end of the year.ASB chief executive Barbara Chapman announced on Monday that she would leave the bank next March "to take some time to think about areas of future interest and challenge".While Australian financial commentators are viewing Chapman's exit in the context of the widely anticipated cleanout of senior executives at CBA following the money laundering scandal, little attention has been given to how New Zealand politics was a likely factor in her decision.As New Zealand's political kingmaker Winston Peters keeps his nation guessing on whether he will anoint National leader Bill English or Labour's Jacinda Ardern to form the next government, it is almost certain that the next parliament will expose Australian-owned banks - ASB, BNZ, Westpac and ANZ - to unprecedented scrutiny.A wide-ranging banking inquiry and measures to improve the competitive position of New Zealand-owned banks were key policy planks of Peters' New Zealand First party at the recent election.No matter which party forms the next government, Peter's influence will likely be sufficient to ensure that his party's grievances against Australian-owned banks will be heeded and acted on in some way.It will also guarantee that Peters will be given a parliamentary theatre to embarrass, cajole and torment senior bank executives over fee increases and lending contracts.Australia's four big banks understand that the politics of banking in New Zealand has entered a new phase, with Peters' activities fuelling new regulatory and reputational risks for their businesses.Peters told Banking Day in July that he was determined to make the Australian banks more accountable to the New Zealand parliament and to increase government incentives for locally owned deposit takers and lenders."The big four Aussie banks are ripping our country off," he said."From the point of view of the national economy it makes no sense to have our banking industry dominated by foreign banks."Peters' agenda for reforming the banking industry is more likely to be advanced under a Labour government, which would also include Green MPs as partners.With political backlashes looming, each of the Australian banks might be prone to viewing incumbent CEOs of their New Zealand arms as political liabilities.Group bosses in Melbourne and Sydney might conclude that they are better positioned to manage new reputational risks by jettisoning long-serving country heads.As recent parliamentary inquiries in Australia have shown, the potential for seething MPs to damage bank reputations is heightened when they are grilling long-serving CEOs.An executive with history can be made accountable, whereas a new face has more political space to wriggle in. According to that logic ANZ's Kiwi boss David Hisco - who has been in the role for seven years - might be a candidate for a promotion away from Auckland.