The Todd Barclay scandal over the taping of his secretary's private conversations matters more than most controversies involving backbench MPs because it has the potential to affect the election result.
That goes to the timing of it: three months out from the election - and the senior stature of the players involved, including Prime Minister Bill English.
The long-running saga erupted yesterday after it was revealed through a text message the Prime Minister sent in February last year that he knew about the taping and did nothing about it other than make a statement to the police during an investigation that was eventually closed.
Here are five ways this scandal matters:
1.THE ELECTION RESULT:
It is 94 days to the election and National was on 47 per cent in last week's Reid Research poll.
The proximity of the publication of Nicky Hager's book Dirty Politics in 2014, two donations scandals involving Winston Peters in 2008, the Brethren's support for National in 2005 and the Hager book Seeds of Distrust in 2002 to the election in each of those years almost certainly affected on the final election result.
The resignation of virtually unknown list MP Aaron Gilmore 18 months out from the 2014 general election barely mattered.
2. The MP's HONESTY:
Barclay repeated denials that he taped his secretary were contradicted by Bill English's statement to the police, in which he said that Barclay himself told English he taped her with a dictaphone when she was on the phone.
Barclay promised the Otago Daily Times he would fully co-operate with a police inquiry and then decided to exercise his right not to and refused any interview with the police.
Barclay's one-term tenure as MP (replacing English who went on the list) has been associated with splits and divisions in the Clutha-Southland seat.
3. THE PRIME MINISTER'S REPUTATION:
Bill English has known since at least February last year that Barclay taped his secretary's conversations and did nothing.
He made a statement to police more than two months after Barclay's confession but that may have been to cover his own butt. Ministers are advised to make statements to the police if ever they are told about a crime having possibly been committed.
He did nothing and Barclay continued to deny the claims publicly. It raises issues of trust and judgment.
The question is whether the MP's resignation, likely to come this afternoon, will cauterise the damage to English, who faces his first party conference as leader on Saturday.
4. THE PARTY:
The National Party leadership has been keen to portray the feuding factions in Clutha-Southland as a "family dispute" that was settled with the re-selection of Todd Barclay in December, despite him being challenged as a sitting MP.
The feud continues, however, over whether the rules were followed and whether the delegates who voted were in full possession of all the facts they should have had.
The Newsroom investigation, which revealed the text message, included audio from the selection meeting in which Barclay denies allegations about the taping.
The police investigation took 10 months and was then closed.
The police released documents to the Herald relating to the investigation under the Official Information Act but they redacted the text message sent by Bill English, which incriminated Todd Barclay, and they did not include the statement English made to them.
Comparison have been made between the vigour of the police investigation in relation to John Key's complaint over the teapot tapes, when he was accidentally taped by a cameraman with a radio mike, and the complaint by Barclay's former electorate secretary Glenys Dickson that she had been taped.
The police are assessing the information that has come to light in the past two days.