Christopher Luxon says nobody should be surprised by his call to rule out working with the Opportunity Party - despite the new position being revealed without notice at the very end of a media conference.In response to a question at his usual Monday briefing, Luxon said he could not work with Opportunity due its advocacy for a land tax. He declined to give a direct yes-or-no answer, but his office later confirmed that amounted to a formal rule-out.Previously when asked, the National leader would say only that a vote for Opportunity looked "like a vote for Labour and the Greens" and that he had not "given them any thought".Speaking to reporters on Tuesday, Luxon insisted the party's position had been discussed among National's caucus and board "for several months"."Pretty obvious to us - and I know a big surprise to you, apparently - but you know, this is a party that wants extreme policy on taxes. We're a party of low taxes. It's not a surprise we don't want to work with them."Luxon also disputed Opportunity's attempt to position itself as a kingmaker which could go with either the left or right."They're as centrist as I am an All Black, frankly," he said.When reminded he was working with New Zealand First, which wanted to buy back BNZ, Luxon replied: "I ruled that policy out, it's all good".He then walked away from reporters, having taken questions for about three and half minutes.In the lead-up to the 2023 election, Luxon called a special media conference to formally rule out working with Te Pāti Māori, as they had "no philosophical alignment".Labour's leader Chris Hipkins says Luxon got caught on the hoof and just made it up as he went along.RNZ / Baz MacdonaldSpeaking separately on Tuesday, Labour's leader Chris Hipkins said anyone watching Luxon's announcement would have described it as "rushed and haphazard" ."I think he got caught on the hoof and just made it up as he went along," Hipkins said."It's clear that... a lot of scrambling went on in the hour or two after that to figure out exactly what their position on it was."But other National MPs reiterated their leader's talking points on the way into their Tuesday morning caucus meeting.National deputy Nicola Willis said Luxon's position reflected "widely held views" across National and did not come as a surprise."It's good we have a prime minister that, when he's asked a clear question gives a clear answer, which distinguishes him from Chris Hipkins, who refuses to be clear about who he would work with."Hipkins has said he will lay out which parties Labour could work with before Parliament rises near the end of September.Campaign chair Simeon Brown said National had long been "very clear" that it would not work with parties with "radical left" policies.Erica Stanford said the announcement had come as no surprise given her discussions with other senior ministers.RNZ / Mark PapaliiChris Bishop said the rule-out was "nothing out of the ordinary" and suggested reporters were "jumping at shadows"."It would be wrong to characterise it as some great big pronouncement. He was asked the question, he answered it."Bishop added that he did not think Opportunity would make it over the 5 percent threshold: "Vibe-based political parties don't go so well."Erica Stanford said Luxon's Monday announcement had come as no surprise given her discussions with other senior ministers."I'm not surprised. The public aren't surprised. No one should be surprised."Three recent polls have put Opportunity near the 5 percent threshold. The latest Talbot Mills Anacta and RNZ Reid Research polls registered Opportunity at 4.7 percent, while 1News Verian had it at 4.6 percent.