People Before Profit is insisting that the medicinal cannabis bill can be amended.
The legislation is now going back to the Health Committee but some parties have suggested that it may contain too many flaws to be workable.
People Before Profit has acknowledged that changes are needed, particularly in providing for the Health Products Regulatory Authority to control the drug.
TD Gino Kenny proposed the bill and believes politicians need to work together to get it across the line.
He said: "The bill is not perfect by any means but it is definitely amendable.
"Political parties have stated that at their debate last week, we can work together, sit down and look at the things we agree on, some things we don't agree on and eventually come to some sort of concensus.
"If it was not amendable, it would not have come to this stage."
A leading medicinal cannabis researcher says it is vital that the drug is legalised.
Professor Mike Barnes from the University of Newcastle will speak at a People Before Profit conference on the bill today.
He says the benefits of the drugs far outweigh any risks.
He said: "There is good evidence now that it helps for example chronic pain, anxiexty and nausea and vomiting after chemotherapy.
"There is a lot of evidence now that it is useful for all those conditions and at the moment there are tens of thousands of people who are using it illegally.
"Why should we make a drug that helps them illegal and make them criminals?"