The authoritative TVNZ-Verian poll, released on Wednesday night, showed Mr Peters' party had reached the threshold for a return to parliament, polling at five per cent support.
They are the seventh pollsters to have Mr Peters' populist party at or above five per cent this year, with an unmistakeable trend line.
Mr Peters - at the ripe old age of 78 - is on the way back.
Should he get there, NZ First looms as a major headache for Mr Luxon.
Since forming the party in 1993, Mr Peters has held office three times, invited into government by National's Jim Bolger and Labour's Helen Clark and Jacinda Ardern.
This time around, he has ruled out working with Prime Minister Chris Hipkins' Labour and is campaigning as the necessary experience that National might need to be a successful government.
Labour has also ruled NZ First out, citing Mr Peters' embrace of anti-trans and anti-vax policies during this campaign.
"Winston Peters and New Zealand First are a force for instability and chaos and that's the last thing the country needs right now," Mr Hipkins said last month.
David Seymour, the leader of National's preferred partner ACT, plainly agrees with Mr Hipkins.
"(Mr Peters has) really got little, if anything to offer for the hopes and aspirations that Kiwis have," he told TVNZ on Wednesday.
Mr Peters has always held views outside of the mainstream, including anti-Islam and anti-migration positions.
This month, he has astounded audiences on the campaign trail by describing Maori as not indigenous to New Zealand.
His rise is a problem for Mr Luxon, who might need his support to get a majority in parliament, leaving him at risk of a fractured government.
In the meantime, Labour will up its attacks on that prospect as it attempts to claw back support.
Mr Luxon has refused to be drawn on whether he could work with Mr Peters or NZ First, leaving the impression he would invite them into government if their numbers were needed.
Mr Luxon has steadfastly said it is premature to consider ruling in or ruling out NZ First as they aren't in parliament and aren't above the five per cent threshold in polling.
However, departing from that logic, Mr Luxon has ruled out working with the Maori Party and the far-right Freedoms NZ grouping.
In May, when he ruled out working with the Maori Party, he said he would "talk about (NZ First) another day".
With NZ First now consistently above the threshold, that day could be rapidly arriving.
On Thursday, under pressure from journalists to "be square", Mr Luxon again batted away how he would manage NZ First in a potential coalition.
"The MMP (electoral) system is given to me and I have to make it work on the other side of the election," he said.
In better news for Mr Luxon, he has overtaken Mr Hipkins on leadership approval ratings according to the same TVNZ poll.
Mr Luxon has a rating of +9, with 44 per cent approval and 35 disapproving, while Mr Hipkins is into negative territory, with 42 per cent approving and 43 per cent disapproving.
