UPDATED 6:14pm: A grinning Winston Peters says John Key's efforts are too little, too late, saying he's feeling "modestly confident" about tomorrow night's vote.

The Prime Minister denies he's been outfoxed by New Zealand First's leader.

Opinion polls have Peters with a commanding lead ahead of tomorrow's vote.

National's Mark Osborne says his party had to go through a selection process.

"That put us two or three weeks behind Winston and others getting out there, so we've had to catch that up."

Winston Peters declared his candidacy on February the 27th, one day before Mr Osborne was selected as the National Party candidate.

The Prime Minister initially said New Zealand First's leader had a zero chance of winning tomorrow's Northland by-election.

The National Party has continually attacked Mr Peters in this by-election campaign by saying he can't force change if he's not in government.

But the New Zealand First leader says it's rubbish, he can make things happen, and has before.

"I delivered the Tauranga bridge when I wasn't even in Government. Have you forgotten that? Toll free, second Tauranga bridge."

The Prime Minister has spent the last two days of the Northland by-election campaign sticking by his candidate's side, hoping he can salvage things and hang on to the seat.

The New Zealand First leader says he shouldn't have bothered because Northland voters have made up their minds.

People here have made up their mind. They've had it to their eyeballs. They want change."

Winston Peters has called National's Steven Joyce "the campaign manager from hell".

Even though the polls are saying Mr Peters is ahead, John Key says that's not the view he had when he was dining out in Kerikeri last night.

"I walked around every single table. There were 50 people there. In that restaurant, there wasn't a single table that said they either hadn't voted, or wouldn't vote for us. It's a pizza place so maybe you might argue some of them were more of our voters."

Meanwhile, Labour's candidate for the Northland by-election is still hard at it campaigning, despite being a very distant third in the race.

Andrew Little's hints to Labour voters to give their tick to Winston Peters seem to have got through.

But his candidate Willow Jean Prime is pushing through to the final whistle - today visiting Mangonui School.

"I'm still out and about campaigning on the ground, talking about issues that are important to Northland and to our local communities."

Willow Jean Prime says the attention Northland has received from the by-election can only be a good thing.