"I think the New Zealand public is sick of games, of people talking in rhymes and riddles," he said yesterday, and he was very probably right.
As press conferences go, the one he called to announce the date was one of the most forthright on record and he also cleared away speculation about National's attitude to Winston Peters and the New Zealand First Party.
"I don't see a place for a Winston Peters-led New Zealand First in a government that I lead," Key said.
"If Winston Peters holds the balance of power it will be a Phil Goff-led Labour government."
That doesn't leave any room for doubt.
Key is taking the same gamble he did before the 2008 election, when he ruled out working with Peters.
At that time there was a real chance NZ First would get back into Parliament, and it very nearly did.
Key later said that on election night he had been ready to concede defeat to Helen Clark if Peters held the balance of power in Parliament.
The risk isn't so high this time.
Peters is campaigning to get back but it is much more difficult now he doesn't have the publicity platform of the debating chamber, and with no chance of winning an electorate seat the party will have to cross the 5 percent party vote barrier.
It isn't impossible, but it is a hard task and Key's announcement hasn't made it any easier.
The effect of his decision to shut the door on Peters is that voters who like NZ First but don't want a Labour government might think twice about backing Peters.
The NZ First leader knows this, which is why he was quick to say yesterday he hadn't suggested his party wants to go into coalition with either of the main parties.
"We also have the option of sitting on the cross-benches acting as a watchdog for the people and getting them a better deal from whoever is in government," he said.
Peters is likely to push this point right through the campaign to counter key's "no deal" position.
Key has also deprived him of a tactic NZ First has used in previous elections -- refusing to say which of the main parties it prefers so it can draw votes from both of them.
At his press conference, called during National's first caucus meeting of the year, Key set out the battle lines for the election.
"National will be campaigning on our record as responsible managers of the economy," he said.
"We're taking clear steps to get the country's debt under control and put the right incentives into the economy to drive faster, real growth."
Goff laid out his election wares as well.
"Labour will campaign on the issues that are affecting New Zealanders most. We know that people are worried about the soaring cost of living with prices rising much faster than wage -- that will be the key election issue," he said.
"They want to cut spending on hospitals and schools. We want to grow jobs, slow down the rise in the cost of living and make sure that we've got growth in the economy."
Key was right about the clear choice. In this election there are stark differences between National and Labour.
The Government is going to keep an even tighter rein on spending this year and the May budget will have less new money in it than the last one.
Key and Finance Minister Bill English believe there's been a big change in public attitudes since the international recession and voters don't want to hear spending promises -- which is why they keep saying Goff has so far committed a future Labour government to about $5 billion.
Goff says the economy is being mismanaged and Labour would borrow less than the Government is now, and still be able to afford a tax free zone for the first $5000 of income, the removal of GST from fruit and vegetables and restoration of cuts in early childhood education.
Key says voters are ready for "a grown up debate" about the economy and the need to cut government spending. Today's announcements are evidence he believes he is right.
