A former National Party MP says speculation over the party's leadership is "divisive and corrosive".Prime Minister Christopher Luxon has called for an "urgent in-person meeting" on Wednesday morning - citing media reports and conversations about further speculation on his leadership.Luxon survived a caucus leadership vote in April but as National struggled in the polls in recent months, rumblings of dissatisfaction refused to go away.Former MP for Pakuranga Maurice Williamson told Checkpoint he'd seen a number of leadership challenges and changes in his 30 years in Parliament.He said he currently saw only two or three standouts for a new leader."Erica Stanford is - in my view - one of the best performing ministers. There is always talk in the media of Chris Bishop being in there. I think Mark Mitchell could easily be an outstanding candidate for it but I don't think he wants it," Williamson said.Williamson said he felt the prime minister had "upped his game", especially in his dealings with the media."He's learnt to be more straightforward in answering questions. I don't hear him anymore going 'well what I'm trying to say to you here, now, is ...' and at the end you don't know what it was," Williamson said.He said some list MPs might have felt a change of leadership could give the party "a bump" in the lead up to the election."Jacinda Ardern certainly picked it up in 2017."So they'd be hoping that bump will give them a few more entitlements from their party list because the members in the National Party caucus right now who are seriously in danger are their listies [sic]."Based on the current numbers - and how many constituencies I think they'll win - I don't think they'll win any list places at all and they're likely to have two or maybe even three more constituencies than their party vote would entitle them to."In which case you get a three seat overhang and the Parliament actually has to grow from 120 to 123 members."So people like Nicola Willis, Gerry Brownlee, Paul Goldsmith [and] Nancy Lu. They must be the one's that are really concerned about where things are," Williamson said.Maurice Williamson spent 30 years in Parliament.VNP / Daniela Maoate-CoxHe said a second "reheat" of challenges to the party leadership would likely have a poor effect the party vote in November."The ordinary person on the street - who's suffering from prices that are killing them and worrying about a whole range of other issues - doesn't like to see the caucus squabbling and fighting amongst themselves - and who can keep a job and who can't - because that's not what's important to them," Williamson said.He said the dissent was enough for Luxon to need to address the broader caucus rather than dealing with individuals."It's clearly enough that he's taken it seriously because normally you'd just call in the one or two detractors and say 'this stops now or I will deal to you'."But obviously he wants them all there."Williamson said it the meeting would be difficult for caucus members."You've got to stand up and face the music and be strong enough to say what you think is good and bad."Get on the wrong side of that windshift and it can cost you heavily when the new allocation of jobs come," Williamson said.Williamson said "the rumor mill" was unlikely to be a true indicator as to who would put their hand up with enough support."I don't think anyone can go into that meeting tomorrow knowing what the outcome willl be. Because, even if they've got it tied down at present, some people will lose their nerve about what it might mean in their electorate or their chances of getting back or their chances of becoming a minister."It's just a shame that they haven't been able to just get back to focussing on what matters to the voting public."As soon as you start talking about yourselves in politics you're basically lost because you should be talking about the voters and what you're going to do for them," Williamson said.