Health Minister Jill Hennessy called Deputy Premier James Merlino a "c---" in a text message sent to him by mistake on Wednesday night, it has been confirmed by numerous parliamentary sources.

Mr Merlino, a fierce opponent of the Daniel Andrews government's bid to legalise a strictly monitored euthanasia scheme, had proposed an amendment that would have killed off the bill, long-championed by Labor as a flagship policy.

The amendment was narrowly defeated and it's understood Mr Merlino is angry about the text message from his colleague.

Increasingly frustrated supporters of the bill accused their opponents of deliberate delaying tactics as both sides wrangled over more than 300 proposed amendments to the bill.

Greens MP Ellen Sandell tweeted about "some appalling behaviour" during the sitting.

"Filibustering on assisted dying legislation by Libs and Nats overnight has been really disappointing," she wrote.

Filibustering - a tactic often deployed in the US Senate - is a political move whereby one or more members of parliament debate over a proposed piece of legislation in order to delay a vote, or prevent it entirely.

Mr Merlino's office declined to comment on the text.

A spokeswoman for Ms Hennessy wasn't giving anything away.

"The minister doesn't comment on private conversations," she said.

A tired Shadow Attorney General John Pesutto on Friday morning. Photo: Justin McManus

Former speaker-turned Liberal backbencher Christine Fyffe on Friday morning. Photo: Justin McManus

An exhausted Liberal MP Tim Smith, who opposes the legislation, wants Parliament to be adjourned. Photo: Justin McManus

With AAP