The voting public have long despised "waka-jumping" MPs. Another unfortunate byproduct of MMP - candidates who "coat-tail" into Parliament on the back of a colleague who wins an electorate seat even if their party has not cleared the 5 per cent threshold - has yet to breed quite the same degree of anger. But it is growing. And more so as politicians exploit the provision to engineer the results they want.
With National hoping to coat-tail candidates from other parties into Parliament by throwing up to three electorates their way, Labour leader David Cunliffe yesterday reached for the vacant moral high ground.
He promised a Labour-led Government would make it a priority to take the first steps towards abolition of the coat-tailing clause in the Electoral Act. He also challenged John Key to pick up a Labour private member's bill to that effect and - with Labour's help - get it passed into law before September's election.
In getting the inevitable "no" from the Prime Minister, Cunliffe still stays on the right side of public opinion, while Key is very much on the wrong side. A poll taken late last year found more than 70 per cent of respondents wanting to axe the coat-tailing clause and only 13 per cent favouring its retention.
The Labour leader has toughened his stance against such deals in the wake of the formation of the Internet Mana party, saying Labour is going all out to win all seven of the Maori seats.
But Cunliffe's categorical - his word - refusal to countenance electoral accommodations could end up backfiring very badly for Labour.
For starters, it is political convention that changing electoral law is done by consensus because it is fundamental to the country's democracy. However justified, Cunliffe's promise to speedily scrap the one-electorate-seat threshold cuts right across that convention because National and Act would oppose such legislation.
Of more immediate pertinence, Labour could yet need Internet Mana to secure a majority in the next Parliament. But bringing more MPs into Parliament alongside Hone Harawira will likely require that the new umbrella party's leader hold his Te Tai Tokerau electorate.
If Harawira lost, Internet Mana's party votes would go down the gurgler to the huge disadvantage of the centre-left in what is shaping as a very close contest.
But Cunliffe is now hamstrung. If he drops even the slightest hint - even a coded one - that Labour voters should opt for Internet Maori in Te Tai Tokerau, Cunliffe will be deemed an absolute hypocrite.
Not the kind of label you want to be carrying during an election campaign.