Act, meanwhile, dropped to 7 per cent, which Curia principal David Farrar said was the first time the company had showed the party polling below its 2020 election result.
"This poll shows that not only has National stopped bleeding support to ACT, but it has started to gain back some of its former voters who voted ACT in 2020," Farrar said in an email to subscribers to the poll.
"Of course this might just be a harsh sample for ACT, so it would be unwise to conclude this is happening until we get further data."
The Green Party dropped five points to 6 per cent.
TOP, which recently named Raf Manji as its new leader, scored 2 per cent.
Te Pāti Māori was on 1 per cent in the poll and New Zealand First registered 1.5 per cent support.
Ardern rose one point in the preferred prime minister ranking, to 39 per cent, while Chris Luxon rose 11 points to 29 per cent.
"This is a very good result for an opposition leader outside an election campaign," Farrar said of Luxon's rise.
There was also a narrowing in the gap between those who say the country is heading in the right or wrong direction.
In January a net 15 per cent of those surveyed believed the country was generally heading in the right direction, but this had dropped to a net 1 per cent believing the country's direction was right.
The net score is the difference between those who believe the country is heading in the right direction and those seeing it as heading in the wrong direction.
"This is still much better than most countries but does signify potential headwinds for the Government," Farrar wrote.
