National's Amy Adams and Judith Collins out of step with Simon Bridges over 'new taxes' suggestion from Government

National leader Simon Bridges' new line-up has already come a cropper to mixed messages from the party's front bench MPs.

Senior MPs Amy Adams and Judith Collins tweeted scornfully at the weekend after Finance Minister Grant Robertson suggested a targeted tax to pay for infrastructure – something Bridges later said he'd been enthusiastic about as Transport Minister.

On Friday Robertson raised the prospect of using "value capture" to pay for infrastructure such as rail - targeted rates or taxes for those who benefit from the infrastructure in question, such as through higher house values.

Finance spokeswoman Amy Adams and new Housing and Urban Development spokeswoman Judith Collins were quick to hit Twitter to deride it over the weekend, describing it as "a new tax".

Adams tweeted: "Another day, another new tax being proposed by the coalition Government. Yet another attempt from Grant Robertson to make everyone else pay for all his promises."

Collins tweeted: "Tax, tax, tax!" and followed it up by saying, "Maybe we should just rename Tax as 'Value Capture'".

When Bridges was asked on Sunday for National's position on value capture he replied, "I think it's good".

He said the former National Government had been "moving in that direction" and he had sought advice on it when he was Transport Minister.

"I was certainly excited about doing more. So I think it's good news that [Robertson] has come to the realisation that he doesn't have enough but the infrastructure needs to be built in New Zealand and some of these things such as value capture, PPPs and other private sector initiatives can play a role."

Told of Adams' and Collins' tweets, he said the election happened before any decisions were made on it.

Housing and Transport Minister Phil Twyford said it was interesting the so-called "new generation" of National were more reactionary than Steven Joyce and Simon Bridges "who were actively exploring land value capture as a way of funding projects like light rail".

Adams said she believed Bridges was referring to Robertson's wider concession that other forms of finance were needed rather than just the state, such as PPPs.

"We support the fact that Labour are now exploring things like public-private partnerships, we think that's sensible.

"What I would say is to start piling up new taxes one on top of the other is something they would have to be cautious of because a government's first job is to control its spending before it looks to just tax its way out of meeting its promises."

Labour has previously ruled out using public-private partnerships for things like schools, hospitals or prisons but is now facing a massive infrastructure bill and has to make decisions on whether to continue with programmes National had proposed from Waikeria Prison to school upgrades.