"What we saw yesterday was truly desperate stuff from Judith Collins," Bridges says.
"I think it shows that she'll go to any length to hold on to her leadership of the National Party.
"There's a huge amount I want to say about what happened yesterday and how wrong it was and I assure you I will but I want to talk to my caucus first and be very clear with them about what I think, and what I think should happen for the National Party."
Bridges says he asked for a caucus yesterday when Judith Collins was still in the precinct "but she wouldn't have a caucus yesterday, finally we have one this morning".
He says he'll answer more questions after the 9am caucus today.
Former National Party leader Simon Bridges is expected to make a statement shortly after his shock demotion by leader Judith Collins.
Collins demoted Bridges to the back benches over a five-year-old complaint about lewd comments at a party function.
RNZ has been told Waitaki MP Jacqui Dean made the complaint in early 2017 and Bridges was spoken to, and then personally apologised.
Collins last night said she had only just learned how serious the complaint was and had no choice but to act.
The shock demotion, announced in a late evening media release, follows months of speculation that Mr Bridges may challenge for the leadership.
National Party MP and Covid-19 response spokesperson Chris Bishop told Morning Report he was sure there would be a caucus meeting of some sort today.
Bridges did not to his knowledge try to call a caucus meeting yesterday, Bishop said.
"Judith enjoys the support of the caucus," he told Morning Report.
"Clearly we have an issue we need to ventilate and talk about which I'm sure will happen this morning.
"Pretty interesting evening last night with a press release coming out like that so clearly we're going to want to talk about that.
Bishop said no colleagues had asked him to challenge for the party's leadership, and asked if he would, he said he was just getting on with his job as Covid-19 response spokesperson.
"I've got more than enough work on my plate"
Collins is expected speak to media at 10am along with the Jacqui Dean.
In last night's media release Collins said her move had the unanimous support of the board of the National Party.
Bishop confirmed that under party rules a leader was not required to seek the board's approval to remove portfolios from a shadow minister.