That was until polling showed the referendum was unlikely to pass.
"I just feel a bit helpless, really," Dr Clare said. "I thought it was going to pass, I really did, and then the last few polls have been really disheartening.
"Then this NZMA stuff came out and I wondered, what can be done here.
"I was surprised about the NZMA's stance on it."
The NZMA had an existing policy formed in 2012 opposing the legalisation of recreational cannabis, but advocating for a decriminalisation of the drug.
While the policy had been reiterated since then, Dr Clare said the age of the policy also baffled her.
"If you have a statement from 2012, you're unable to take into account some of the evidence from countries that have subsequently legalised cannabis and have seen some evidence of harm reduction with the legalisation model."
Dr Clare posted on doctors' groups on Facebook, asking who would be willing to put their name behind the campaign to legalise recreational use of cannabis.
She said it should be clear cut that legalisation was the best outcome, and that decriminalisation would not go far enough.
"My assessment of the evidence I've seen, it's pretty overwhelmingly in favour of legalisation and that's the same conclusion that the Public Health Association has reached.
"But I also think, in the New Zealand context we have an added imperative to legalise because of Te Tiriti o Waitangi.
"We currently have this situation where Māori are disproportionately being harmed by this criminalisation of cannabis, and as Treaty partners we have to try and rectify some of that inequity."
Dr Clare said not all doctors wanted recreational cannabis legalised, and there was a very real split between medical professionals.
She said no group could claim to be speaking on behalf of all doctors, but wanted to make it clear that a large proportion of doctors did support legalisation.
