Labour leader Andrew Little has given supporters a hint that they can vote for Winston Peters in Northland, but he rejects any comparisons to National's "dirty deals" in Epsom.
Mr Little said yesterday that the byelection now appeared to be a two-horse race between the New Zealand First leader and National candidate Mark Osborne.
He said Labour's candidate, Willow-Jean Prime, would continue to campaign and he would travel to Northland to support her.
But he added that Labour voters should "think carefully about how they exercise their vote" if they wanted to "send a message" to the National-led Government.
"The reality is that there are two polls in a row that show there's a competition between the two front-runners, in this case National and New Zealand First. And it's usually typical for a byelection, the race ends up coming down to the two front-runners. I can't ignore that reality, nobody else can.
"In the end, byelections are a referendum on the government of the day. If Northlanders feel they've been neglected and they can't get their roads fixed and those sorts of things then they're going to have to think about how they cast their vote in a way that sends a message to Government."
Mr Little's comments echoed Mr Peters' slogan for his Northland campaign, which is "Send Them a Message".
Mr Osborne said he had expected Labour to back Mr Peters, but he was surprised Labour had taken this approach so early in the campaign. A TVNZ Colmar Brunton poll, yesterday showed Mr Peters and Mr Osborne tied on 36 per cent. Ms Prime was well behind on 20 per cent. If Labour pulled Ms Prime from the race, 51 per cent of Northland voters would back Mr Peters and 37 per cent would back Mr Osborne, the poll said.
Mr Little said yesterday: "This is a byelection where the voters have one vote and it's an area that has been routinely neglected by the National Party and National Party MPs."
Upgrade of three Northland bridges likely
The National Party is expected to announce it will upgrade Northland's single-lane bridges to two lanes in a bid to bolster its support ahead of the byelection.
National ministers and byelection candidate Mark Osborne are making a policy announcement at Kaeo this morning. It is understood they will commit to upgrading three single-lane bridges in the Northland electorate, at Matakohe, Taipa and Kaeo.
National's main rival in Northland, New Zealand First leader Winston Peters, has accused the Government of neglecting the region, in particular its roading.
Last week, he said four National MPs had failed to upgrade Matakohe and other bridges from a single lane.
The upgrades to the three bridges were described as "priorities" in Northland's Regional Land Transport Plan.
Construction of two-lane bridges at Taipa and Kaeo had estimated costs of $4 million. Construction of a new bridge at Matakohe could cost up to $15 million.
Former Northland MP Mike Sabin had lobbied for years for the bridges to be upgraded to two lanes, because local community members said they were unsafe and an impediment to economic growth. Several fatal car crashes have happened at the Matakohe Bridge, which one community lobby group described as a "death trap".