Simon Bridges suggested Prime Minister Jacinda Ardern is "making excuses for her Ministers' appalling behaviour" due to them being "stressed" during an animated exchange between the pair in Parliament's Question Time today.
Mr Bridges went on the attack against MPs Shane Jones, Ron Mark and Damien O'Connor over stories which have been in the media recently.
His comments came as Regional Economic Development Minister Shane Jones declared a conflict of interest over a $4.6 million funding boost for a Northland organisation.
Veterans Affairs Minister and NZ First MP Ron Mark has been accused of suggesting he would cut funding to a veteran's organisation if they don't support NZ First.
While Labour MP Damien O'Connor has also been accused of suggesting withholding funding to Animal Evac NZ if they didn't stop criticising the Government.
Both Mr Mark and Mr O'Connor have denied the claims.
Today, Mr Bridges asked the Prime Minister if the "behaviour of Minister's, Jones, Mark and O'Connor" had adhered to the highest ethical standards set out in the Cabinet manual?
Ms Ardern answered that "Based on the advice I have received, yes". She then listed off the positive work the three Minister's were undertaking in their respective portfolios.
"Is she making excuses for her Minister's appalling behaviour because they're a little bit stressed with the rigours of Government?" Mr Bridges then asked.
"No, I think you'll find that was actually a list of achievements," Ms Ardern responded.
In the case of Shane Jones, the Minister admits he should never have stayed in a meeting where funding was signed off for the Opononi Tourism Project due to his conflict of interest.
However, he says the opposition is "making a mountain out of a molehill" over the issue as he didn't sign off on the funding himself.
A video released to Stuff showed Ron Mark speaking to veteran charity No Duff in December, which National said entailed the Defence Minister using his position to push for votes.
In the video Mr Mark says: "When I look at the polling results of my political party NZ First, then the veterans, the Defence base, you guys haven't supported us.
"At all," Mr Mark said.
He responded to the accusations today, saying his comments were "misconstrued".
Damien O'Connor denies Animal Evacuation New Zealand co-founder Steve Glassey's claim that he sent any "veiled threats" to the organisation over their criticism of the Government that could be tied to funding.