The Prime Minister doesn't want to share any opinions he might have on the United States presidential election and hopeful Donald Trump but he is taking a stand on Britain's referendum on European Union membership - he wants the UK to stay in the EU.

Speaking at his post-Cabinet press conference today (Monday), John Key said it was up to the people of the US to decide who their president would be and he would work with whoever they chose.

"In the end, whoever becomes the next president of the United States of America, I'll be trying to work constructively with.

"I do that with every country that we have a relationship with and that's because that's my responsibility."


Mr Key was not concerned by the number of presidential candidates who opposed the Trans-Pacific Partnership trade pact New Zealand and the US are parties to.

"I take all the slogans that are made on the campaign trail with a grain of salt, to be frank."

The PM, who has played golf with President Barack Obama, was asked if he could imagine playing with Mr Trump. "Let's wait and see who wins the election first," he responded.

Mr Trump owns many golf courses, Mr Key acknowledged, and last week, the US magnate told Patrick Gower of MediaWorks that he admired Kiwi golfing legend Sir Bob Charles.

Today, speaking on Britain's European Union referendum on June 23, the PM said: "When Britain is part of the EU, it gives us a strong and supportive voice in the EU."

He said New Zealand was trying to negotiate a free-trade agreement with the EU, and Britain had been a really strong supporter of New Zealand's case. Germany had too.

"If you are asking, from New Zealand's perspective, are we better off with Britain as part of the EU or worse off, I think on balance we are better off, but the British people will decide whether they want to stay or go."