National claims the Government is sending out a big cry for help with its latest plans for KiwiBuild.

Housing Minister Phil Twyford says he's had a lot of support for his idea to prefabricate many of the homes.

"The Government will formally invite expressions of interest from construction firms and investors - both internationally and in New Zealand - on how we can work together to establish a modern, offsite manufacturing house-building industry in New Zealand," he told Newshub Nation on Saturday.

But National Party housing spokesperson Judith Collins says the minister has resorted to the private sector because the Government can't manage the programme.

"It's not that prefabs is a bad idea, because it's not," she told Newshub. "It's the fact that he still can't actually do anything himself. He's having to get the private sector to help him with it. He's asking for expressions of interest. It's a big cry for help.

"I guess at least he's admitting he can't do stuff himself, but I just think it's all a bit late really."

Labour promised to have 100,000 KiwiBuild homes built in 10 years, starting July 1.