Electoral reform is back on Parliament's agenda.

MPs will tomorrow debate a Members' Bill from Labour MP Iain Lees-Galloway that aims to remove the current coat-tailing provision from MMP elections.

He said "the one seat threshold has become something that has been rorted."

"Political parties are making deals with other parties simply so they can bring in extra list MPs, even though there's no chance of them meeting the threshold."

Currently the only party in Parliament who have successfully taken advantage of the rule is the Maori Party, who brought Marama Fox in on the list after Te Ururoa Flavell won his electorate.

The most famous examples of attempts to take advantage of the rule are ACT's use of the Epsom electorate, United Future's use of Peter Dunne's Ohariu electorate, and Internet-Mana's attempt to retain Te Tai Tokerau and bring in MPs on a shared list.

None of those examples in the 2014 election were successful.

The bill to be debated will also reduce the MMP threshold for getting into Parliament from 5% to 4%.

Both are measures the Government has previously blocked from further progress.

But Mr Lees-Galloway said there's a public desire to see changes made.

"In order for us to have a robust electoral system that people have faith in, I think we need to set aside party politics, and make sure that our electoral system is one that people believe delivers an appropriate result."

Under a lower threshold the outcome of the 2014 electorate would not have changed. The Conservative Party were closest to making the 5% threshold, winning 3.97% of the vote.

However, in previous elections both provisions have had a greater effect.

In 2008 New Zealand First failed to win any seats, despite winning more than 4% of the vote. That same year the ACT Party's then leader Rodney Hide won Epsom, and brought in a further 4 list MPs.

Electoral reform's back on Parliament's agenda.

MPs will tomorrow debate a Members' Bill from Labour MP Iain Lees-Galloway that aims to remove the current coat-tailing provision from MMP elections.

He said "the one seat threshold has become something that has been rorted."

"Political parties are making deals with other parties simply so they can bring in extra list MPs, even though there's no chance of them meeting the threshold."

Currently the only party in Parliament who have successfully taken advantage of the rule is the Maori Party, who brought Marama Fox in on the list after Te Ururoa Flavell won his electorate.

The most famous examples of attempts to take advantage of the rule are ACT's use of the Epsom electorate, United Future's use of Peter Dunne's Ohariu electorate, and Internet-Mana's attempt to retain Te Tai Tokerau and bring in MPs on a shared list.

None of those examples in the 2014 election were successful.

The bill to be debated will also reduce the MMP threshold for getting into Parliament from 5% to 4%.

Both are measures the Government has previously blocked from further progress.

But Mr Lees-Galloway said there's a public desire to see changes made.

"In order for us to have a robust electoral system that people have faith in, I think we need to set aside party politics, and make sure that our electoral system is one that people believe delivers an appropriate result."

Under a lower threshold the outcome of the 2014 electorate would not have changed. The Conservative Party were closest to making the 5% threshold, winning 3.97% of the vote.

However, in previous elections both provisions have had a greater effect.

In 2008 New Zealand First failed to win any seats, despite winning more than 4% of the vote. That same year the ACT Party's then leader Rodney Hide won Epsom, and brought in a further 4 list MPs.