New Zealand First had an eventful annual convention on Sunday, 25 years after the party was established.

Delegates want a new law that would ensure migrants and refugees speak English and "respect New Zealand values" or be sent home.

In Tauranga, they voted in support of introducing a new Bill that included respect for gender equality, religious freedom and New Zealand law.

Leader Winston Peters sniped at the party he rejected in coalition talks - and in particular, National leader Simon Bridges.

"National is leaderless," he said. "It's moribund and it's vacuous and it's got bitter and jealous."

He also made the bold prediction that Mr Bridges will be gone before the next general election.

"No party can stand that sort of lack of leadership and survive long."

A spokesperson for Mr Bridges told Newshub he wouldn't dignify Mr Peters with a response - but there's a familiarity about some of the values.

"I think people who don't adhere to the wishes of our people and our Government should be asked to consider going back to their own country where they came from," Wairarapa delegate Nigel Melville told Newshub.

He wants a return to New Zealand values from immigrants and refugees.

"There's nothing more embarrassing to a Kiwi, a genuine Kiwi, to walk into a shop and go and buy something behind the counter and all you get is foreign language."

Mr Melville had plenty of support at Sunday's event.

"There was too much challenge to our way of life, and anyone who comes into the country needs to absorb what we have," one delegate said.

"When in Rome, do as the Romans do."

The delegates voted to support the party introducing the Respecting New Zealand Values Bill, which would ensure migrants and refugees "respect New Zealand values" or be sent home.

But there were some dissenting voices.

"There can be a hint of cultural bias and cultural prejudice, and it can lead to other things that are not so acceptable in society," Northland delegate Mere Mangu told Newshub.

For 25 years, New Zealand First has trodden a fine line with its stance on immigration. The question is now, with this remit, has it finally crossed that line? Mr Peters doesn't think so.

"If somebody's over here, wants to change this country and doesn't want to submit to this country's law, who's bigoted when it comes to religious tolerance, who thinks women are cattle and second-class citizens, that person should not be here, sorry."

He said New Zealand First is tracking well in the polls and the Government is unified. But the reality of coalition is if the values remit becomes policy, it may struggle to get over the line with colleagues in the Greens and Labour.

Newshub.