Mark Mitchell says if there is a Judith Collins faction within the National Party, he hasn't noticed it. Speculation is mounting that Collins is planning to roll Simon Bridges. But Mitchell - who also ran for leadership after Bill English resigned - says Collins hasn't made any challenge for the leadership. He told Mike Hosking Bridges received unanimous support at yesterday's caucus meeting. "We emerged from that caucus completely unified yesterday and we are focused on holding this government to account." He says Bridges will emerge stronger because of this. Mitchell says Labour's recent history shows how destructive leadership challenges can be. "We're not going to fall into their trip when they start tiffing out their leaders and they cause deep divides within their caucus. They fractionalised and those factions actually still exist today." Mitchell says that Bridges has made the best decisions over major issues such as Jami-Lee Ross' outbursts and the 'emotional staffer' incident. Stuart Nash, who joined Mitchell on the Pollies, says that his opponent operates well under pressure unlike Bridges. "I like Simon, he's a nice guy, but I just think that Mitch, because of his leadership and professional background, would be a better leader."