It is also possible that Biden will confirm whether the US will send a ship to the Royal New Zealand Navy's 75th anniversary this year, which would break a 30-year impasse.
Key has been discussing the South China Sea dispute with Indonesian President Joko Widodo In Jakarta. Indonesia is not a claimant in the disputed waters but has fishing rights which it wants to preserve.
Biden would have an interest in Indonesia's position, Key said, and would also "get a read-out of the way we're seeing it". New Zealand wanted "cool heads to prevail"in the South China Sea, and it was in no country's interests for the situation to "flare up".
"There will be a way through like every complex issue," Key said. "And the best and most successful way through will be diplomacy and dialogue."
President WIdodo shared New Zealand's desire for peace and stability in the region, he said.
Key also said he was not disappointed that it was Biden, not Obama, making a state visit.
"I don't think it rules out Obama potentially coming, but I've always been in the camp ... that it's been less likely that President Obama would actually get here in his final year of being president."