WELLINGTON: New Zealand Prime Minister John Key unexpectedly resigned on Monday. His departure will affect New Zealand's relationship with the US, its free-trade agenda and its role on the world stage. The country's new leader will face an opposition buoyed by Key's departure as it heads into elections next year. A look at these issues: A reset US relationship New Zealand's military and diplomatic ties with the US weakened in the 1980s after the South Pacific nation banned nuclear warships. Relations improved again over time and became particularly close under Key. The prime minister has a vacation home in Hawaii and played golf there with President Barack Obama. Last month, a US warship visited New Zealand for the first time in more than 30 years, prompting Key to say the countries' relationship was in its best shape since the nuclear ban. A microphone left running at a conference last year picked up Obama telling Australian Prime Minister Malcolm Turnbull that Key was a 'wonderful guy.' Obama also told Turnbull that he and Key 'have become good friends, and not just because we play golf together.' The kind of relationship that develops between President-elect Donald Trump and New Zealand's new prime minister remains to be seen. Bumps in free trade Key has aggressively pursued a free-trade agenda. New Zealand relies on selling dairy products and other agricultural goods abroad to make money, and has signed free-trade deals with China and more than a dozen other countries. Key's government helped craft the Trans-Pacific Partnership, a 12-nation trade pact that Trump says he will withdraw from. Trump's election victory and Britain's vote to leave the European Union seem to indicate widening opposition to free trade. Many people in New Zealand remain skeptical of its benefits. The opposition Labour Party says it favors free trade, but has also been critical of the way Key's government handled the TPP negotiations. Smaller international role Key's stature in international affairs grew over time. His government successfully lobbied for New Zealand to gain a temporary seat on the UN Security Council. Under Key, New Zealand hosted world tournaments for rugby and cricket. He also serves as chairman of the International Democrat Union, an association of conservative political parties. Key managed to forge good relationships with a number of international leaders, including Obama. New Zealand's new prime minister will likely play a smaller role on the international stage, at least at the beginning. Emboldened liberals Key's conservative National Party has won the last three elections, and some liberals were already steeling themselves for a fourth consecutive defeat in 2017. Opinion polls showed the National Party with far more support than its left-wing rival, the Labour Party. And Key was comfortably leading polls for the preferred prime minister. Key's charisma and ability to connect with voters were vital to his party's success, something he acknowledged in his resignation speech. 'Obviously, there's been a brand around me,' he said. 'That's been built up by the people around me and they've allowed that brand to develop, and that's been a factor which has been helpful.' Liberal opponents will feel they now have a better chance to win the next election and change New Zealand's course.