Māori Party co-leader Te Ururoa Flavell won't be abdicating his role, at least until he's helped clear the rubble left from last September's disastrous general election showing.
Dr O'Sullivan, a former New Zealander of the Year, appeared on the show to discuss the effects of gambling on child health, but was drawn into a conversation on his political aspirations.
"I've publicly supported the Māori Party for some time and made statements about my desire to be involved."
Garner went a step further, calling on Mr Flavell to resign and hand the reins to Dr O'Sullivan.
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"You've had a great career, you were minister, but you got smashed at the last election," he said. "You do a handover and here's your man.
"Lance O'Sullivan is the perfect guy for this. Who else could it be?"
But Mr Flavell and co-leader Marama Fox aren't going anywhere, until the Māori Party has rallied from an election that saw it unrepresented in Parliament for the first time since it contested the 2005 election.
The next day, Mr Flavell indicated he would stand down from politics, while Fox lashed out at voters for returning to an "age of colonisation".
Five months later, both are still at the helm, despite a call from former party president Tukoroirangi Morgan, who resigned in December, to stand down.
This week's annual general meeting at Rotorua's Tangatarua Marae will election a new president and vice presidents, but nominations for the leadership will be held over until the party's future leadership structure becomes clearer.
"We're taking it slowly," Mr Flavell told Newshub.
"We'll probably stay in these positions for at least a couple of months, until we've nailed our strategy for the future.
"We want to do it carefully, and make sure we get the planning right and listen to the electorates."
One of the key issues to be clarified is whether the party continues with male and female co-leaders, as stipulated in its constitution.
"Whatever the leadership of the Māori Party looks like, in my opinion, you need a single, strong message coming from, I believe, one leader," said Dr O'Sullivan.
Another contentious point could be whether the party leaders need to hold a seat in Parliament.
If the Māori Party were to capture a seat again, would that MP automatically become leader or could an incumbent retain that role from outside Parliament?
Mr Flavell admitted the party had spoken to several potential leaders, including Dr O'Sullivan, since the election.
"We've had a number of discussions with Lance and other people," he told Newshub.
"He's one of a number of other people who could fill the role."