Although Labour gained ground as more results came in the gap between the main parties remained substantial.
On 75 percent counted, National held 46 percent of the party vote and Labour 33 percent.
ACT held 3.7 percent and Labour's ally the Greens 6.4 percent.
If those figures carried through to final results, National and ACT would hold 64 seats and Labour with the Greens 51.
The Maori Party was heading towards holding five of the seven Maori seats but it would not hold the balance of power.
New Zealand First, which needed 5 percent of the party vote to have any MPs in the next Parliament, was running at just over 4 percent and appeared to be doomed.
National can add United Future leader Peter Dunne to its seat tally, reaching 65, while Jim Anderton will boost the Labour/Greens total to 52.