Mr Key stepped into the breach for him at a Trans Pacific Partnership meeting, a favour that probably helped Mr Key get an invitation to a lengthy golf game with Mr Obama in Hawaii over summer.
"Five hours on a golf course; it's a way of developing a personal relationship," Mr Key said.
Mr Key says he was nudged up the White House guest list this year by Mr Obama.
"I'm not sure the White House schedulers would necessarily want us up the list but the President did."
Mr Key's talks with the President and Defence Secretary Chuck Hagel today and with Secretary of State John Kerry yesterday have given him an inside view of the US thinking on Iraq.
But trade remains the top priority for the two leaders. Advancing a comprehensive Trans Pacific Partnership deal remains the top issue on the leaders' agenda even if it means them agreeing to take more time to do it.
Mr Key yesterday gave a strong message to the US Chamber of Commerce about TPP.
"We could all sign up to a deal, which is not comprehensive, which doesn't see trade access, which is politically palatable but achieves very little and if we do that, we are all wasting our time.
"It takes bit longer to get a better deal, we should do it."
He said the United States' agriculture stood to gain more than New Zealand's.
Mr Key had lunch yesterday with US Trade Representative Mike Froman and came away confident that a comprehensive agreement would be done eventually.
He also met US Federal Reserve chairwoman Janet Yellen where he talked about this week's strong growth figures.
Meanwhile, Mr Key said he did not believe Mr Kerry's reference on Thursday to the safety of nuclear power on US naval ships was putting pressure on New Zealand to revisit its anti-nuclear laws.
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