However, Opposition calls for an inquiry to be conducted as soon as possible may further derail his plan.
Another complication will be the investigation on Dirty Politics being undertaken before the election by the Inspector-general of Intelligence and Security, Cheryl Gwyn, Mr Key phoned Ms Collins on Saturday when a further tranche of emails was released.
The emails appeared to indicate Ms Collins had worked with right-wing blogger Cameron Slater, and others, to remove the then head of the Serious Fraud Office Adam Feeley.
The conversation ended with Ms Collins offering her resignation. Mr Key said if National was re-elected, Ms Collins would not be considered for Cabinet. However, if an inquiry cleared her, she may again be considered for a cabinet position.
The hacked emails appear to show former Hanover Finance executive Mark Hotchin secretly paid bloggers Mr Slater and Cathy Odgers to write attack posts undermining the Serious Fraud Office, Mr Feeley, and the Financial Markets Authority, who were probing his collapsed business in 2011 and 2012.
Mr Feeley is now chief executive of the Queenstown Lakes District Council and could not be reached yesterday. In a written statement, Mr Feeley says throughout his time as chief executive of the SFO, he believed the work of the SFO always enjoyed the support and respect of the Government.
Mr Feeley said in his years as a public servant he strived to ensure, and believed he had, an entirely professional and constructive relationship with ministers he worked with.
Finance Minister Bill English said yesterday the implications of the emails would be serious if they were borne out. That was why the prime minister had initiated an inquiry.
Asked on TV One's Q+A about the allegation Mr Hotchin was behind the smear campaign, Mr English said it was bizarre.
''If that is linked through the email to any kind of ministerial conduct as is implied, that's a serious issue but we've yet to see whether an email written by the blogger is correct or not and an inquiry will deal with that.''
Labour leader David Cunliffe said evidence crucial to any inquiry by Judith Collins and other National ministers and staff must be protected. The State Services Commission must order Ministerial Services to stop any computer files being deleted.
All documents in the Justice Minister's office needed to be immediately secured. Judith Collins' closest advisers have lost their jobs and should surrender their cellphones and laptops.''
A full commission of inquiry must be held into the connection between National ministers and Whale Oil blogger Mr Slater, Mr Cunliffe said.
The 17,000 Kiwis who lost their savings in the collapse of Hanover Finance would be shocked at the alleged connection to Mr Hotchin, he said.
Mr Key was campaigning in Auckland yesterday and crowd scenes posted on social media showed he was receiving a warm welcome. He believes Ms Collins' resignation will be viewed positively by voters.
It may give him a chance to start talking policy and get into a better mood for the remaining election debate with Mr Cunliffe.
On the first debate last week, Mr Key looked distracted, annoyed, and ill at ease. Presumably, Judith Collins was on his mind.
The next debate is tomorrow in Christchurch, hosted by Stuff.co.nz and The Press.
Investigations by the Otago Daily Times, to be reported more fully later this week, found an underlying resentment to the pace of the rebuilding of houses in Christchurch, particularly east of the Square.
The leaders answer questions from the floor and Messrs Key and Cunliffe will need the facts at their disposal.
While the rebuild bill has soared to $4 billion, general dissatisfaction is being shown by some parts of the community about the state of their houses and lives. The push for commercial rebuilding has not impressed those living in damaged houses for four winters in a row.
Labour has promised much in Christchurch but needs to convince voters it can do what the Government has so far failed to achieve.
In the same debate in 2011, Mr Key destroyed former leader Phil Goff with his now famous ''show me the money'' quip. At the time, Labour had not released its full fiscal costings.
This time, Labour has done its costings, pulling back on six policies it planned to release but now says it can no longer afford because of the Treasury downgrade in the pre-election fiscal update.
National is still ahead in public opinion polls, but support has been slipping as the so-called teflon veneer of Mr Key started slipping.
He has less than three full weeks to regain momentum, brush off annoying questions and allegations being asked and made about his office, staff and links with bloggers.
Mr Cunliffe has a difficult choice to make - push through with the corruption and inquiry angle, or try to prove to voters Labour is indeed the government in waiting.
