John Armstrong: It'll be centre-right on the night, with a few strings

National vote will increase, but volatile elements could hold coalition surprises. Photo / Dean Purcell

It's put up or shut up time. The final day of the campaign means it's time to make a stab at the election result.

So here goes. National's share of tomorrow's vote will be higher than the nearly 45 per cent the party secured three years ago.

But it will more than likely fall short of what will be required for it to govern alone.

However, the next Government will still be a centre-right one. National's allies should still be returned in sufficient number to guarantee a new minority National Government the required majority on confidence and Budget motions in the next Parliament.

But there are complicating factors.

The odds on New Zealand First crossing or not crossing the 5 per cent threshold are now so even it's anyone's guess.

Winston Peters' party is rating at 5.2 per cent in today's Herald-DigiPoll survey. However, the Herald pollsters caution there are signs that support will tail off.

Peters would be feeling more comfortable if his party was polling around 6 to 7 per cent.

He can take some comfort in the polls traditionally underestimating backing for his party.

On balance, he may have left his run too late and his new-found support may be illusory and not translate into votes.

The big story on Saturday night could be the rise of Colin Craig's Conservative Party, which registered at 2.4 per cent in last night's One News-Colmar Brunton poll.

National will be worried about a repeat of United Future's coming from nowhere in the final week of the 2002 campaign to capture nearly 7 per cent of the vote.

Craig's party won't do that well. But it could be a significant nuisance factor.

The other complication is the "don't knows", who rose to 12 per cent in last night's 3 News-Reid Research poll.

Once those "undecideds" were probed on their likely preference, National's support dropped from nearly 51 per cent to close to 47 per cent.

That explains National's last-minute advertising blitz to get its traditional vote out.

But unless the polls are very wrong, Key should still be able to claim victory tomorrow night.

He can rely on enough National supporters doing the right thing for their party in Epsom - even if they have to hold their noses as they tick John Banks - Act on the ballot paper.

A Banks victory might bring Don Brash into Parliament. But that will be Act's limit.

If Peter Dunne makes it back, that will be a bonus for Key.

The Maori Party is crucial to him. It will be returned with two, three or even four MPs. They may not commit on the night, but Tariana Turia and Pita Sharples will probably ensure Key gets their party's backing on confidence and supply.

At worst, the Maori Party could abstain. That would complicate things for National, especially if New Zealand First gets back.

But Key would still be able to govern - just.

Labour will post its worst result since 1996 when it got only 28 per cent of the vote.

Labour could go even lower still. If the Greens cannot capitalise on Labour's current predicament, they never will.