He said he did not take the high levels of support in the polls for granted. "You have my strong commitment that I will do everything I can to lead a strong Government and a strong National Party as we face the next two and a half years until the 2017 election."
Last year, Mr Key revealed to biographer John Roughan he had considered stepping down in 2012 after a year dominated by issues such as the teapot tapes and Kim Dotcom's donations to John Banks.
Speaking to the media yesterday, he said events such as the Northland byelection loss and troubles over the ponytail pulling had not had the same effect: "Definitely not."
Mr Key spent much of his speech focusing on bread-and-butter issues.
It was his first visit to Northland since the byelection victory by NZ First leader Winston Peters in late March.
In Opua, he announced an extra $3 million towards the Twin Coast cycle trail from the Bay of Islands to Hokianga.
Mr Peters, the local MP, was snubbed for the cycle trail event, which Mr Key attended with Far North Mayor John Carter and Green Party co-leader Russel Norman.
Mr Peters said Mr Key's promise was hollow because land and access rights were delaying the trail.
"Northlanders are not going to be persuaded by a $3 million statement which they may never spend because of those issues."
Minister is staying put
Prime Minister John Key says a Cabinet minister whose brother is reportedly facing indecency charges is willing to step down if needed but Mr Key was confident the issue could be managed without that happening.
A report said a Cabinet minister's brother would appear in court tomorrow on child indecency charges. An injunction meant neither the minister nor the man accused could be named.
Mr Key said the minister had advised Mr Key's office about the situation as soon as the minister knew about it. Mr Key had sought advice on it.
"The advice I've received is that there is no conflict of interest and the issue can be managed. People appreciate that Cabinet ministers, like anyone else, have family but I'm quite confident the position can be managed."
He said the minister was happy to step down if that was what was required. "But that isn't the advice I've got."