The Government killing off a capital gains tax today was a "massive loss" for the Prime Minister in her so-called year of delivery.
Jacinda Ardern announced this afternoon that the Government would not be implementing the tax.
Bridges said that Ardern could not get a CGT across the line even though she was at the "apex" of her power.
"People will be asking questions about that."
He said National's "relentless opposition" had a part in the decision and it was a "big win" for National, and an embarrassment for the Government.
Bridges said millions of dollars had been wasted, and businesses had had the confidence "knocked out of them".
"The weakening economy needs a plan from the Government.
"We've embarrassed the Government out of a CGT and that is good for New Zealanders."
National had been the "loudest" voice opposing a CGT, and without it, NZ First would have supported the CGT, Bridges said.
Winston Peters has flatly denied this, saying that time was up on Bridges' leadership.
Bridges said a CGT would have sapped the confidence of businesses, and the mere debate about it had discouraged businesses in the last few months.
He said his leadership was secure and that National still had the support of 40 per cent of New Zealanders, according to the latest 1 News Colmar Brunton poll.
"I feel really comfortable and confident in my leadership. Today is a real win for National under my leadership, and I'm focused on that."
Asked about whether the "numbers were firming up for Judith Collins", Bridges said he was sure that was not the case.
He said he expected to be the National leader through to the election.
He would not say whether he had asked caucus members for feedback on his leadership.
He said he was not nervous "at all" about murmurings about his leadership.
"I'll be leading this great party right through to the election, and we're planning on winning."
Even though the CGT had been thrown out, Bridges said there were signs the economy was weakening and the Government needed a plan to grow the economy.
"New Zealanders can't trust Labour on tax."
He said National MPs would be "feeling really good" about his leadership after today's backdown on a CGT.