Labour is to seek leave to get a member's bill on changes to the MMP system system put before Parliament.
The Government on Tuesday said it would not be making any changes to the voting system because political parties could not agree on the proposed changes.
The surprise move followed months of work by the Electoral Commission which recommended changes to the thresholds for parties to enter Parliament and cost an estimated $1.4 million.
Labour's bill, which is already in the ballot, seeks to reduce the threshold at which a political party gets elected to Parliament from 5% to 4% as recommended by the commission.
Justice Minister Judith Collins sent two letters to the Labour Party in the last few months, saying she wanted a collaborative process to make changes.
Labour leader David Shearer said there has been no further engagement and now Ms Collins is claiming she doesn't have the numbers.
He says Labour has never stated bottom lines on changing the MMP system and wants National to allow Labour's bill to be tabled so the threshold issue can go to a select committee.