Prime Minister Jacinda Ardern is defending Cabinet's call to create a new unit within Government to oversee and ensure the success of new major spending decisions.

The Opposition has already been critical of such a unit, saying the job of managing spending directed by Cabinet already sits with Government ministries and agencies.

National leader Judith Collins called it a "vote of no confidence" in a Government which "couldn't even deliver Uber eats".

And Act leader David Seymour said Ardern has given a hospital pass to this unit and had essentially admitted that she doesn't have confidence in her ministers to do their jobs.

"We had the so-called 'year of delivery' now we have the 'unit of delivery'."

But Ardern told media this morning that, given the enormous amount of new spending in this year's and last year's budgets, such a unit was required.

She said it was "just good practice".

"We wanted to make sure that, given the complexity of some of those projects, we did have extra support available thought the form of that implementation unit."

She said the unit was not a large body but it would support agencies and departments which will have to rapidly increase the amount of groundwork and deployment they are doing.

"This is just an extra support mechanism we can put in given we haven't asked our departments and agencies to deliver projects of this scale before."

In response to Covid-19, the Government rolled out tens of billions of dollars' worth of spending in last year's budget - $50 billion to be exact.

And it appears the Finance Minister Grant Robertson plans on earmarking even more Covid spending in this month's budget – "this will be a Recovery Budget", he told a business breakfast this morning.

He told those in attendance that the new implementation unit would monitor and support the implementation of a small number of initiatives, particularly where multiple agencies are involved.

This includes areas such as mental health, infrastructure, housing and climate change mitigation.

Speaking to media before National's caucus meeting, Collins said setting up the unit was a vote of no confidence in the Government and its management of its ministries.

But she said that Robertson and Ardern were right to have no confidence and they "couldn't even deliver Uber eats".

She said Cabinet should be in charge of implementing the promises and the decisions of Cabinet – "not some group that is having to be brought in".