New Zealand First leader Winston Peters says the Government could fall over its decision to veto a bill boosting paid parental leave.
Finance Minister Bill English says the bill would be too costly and the Government can't afford it.
Mr Peters told Morning Report that the Government is not right to rule against the majority of parliament and and the matter could become a confidence issue.
But he said New Zealand First will not give its view on the bill, until it's had time to have a decent look at the costs and time period proposed.
The bill, by Sue Moroney (Labour), proposes to increase paid parental leave from 14 weeks to 26 weeks by 2014.
The Prime Minister's office has issued a list of the number of times Governments have vetoed legislation since 1999.
Labour used the veto 31 times while it was in Government from 1999 to 2008, including on paid parental legislation changes proposed by the Opposition at the time.
During the last term of Parliament, the current Government used the veto five times.