ROGUE Labor backbencher Brenton Best has been given an ultimatum to "put up or shut up" but won't be disciplined for publicly calling for Premier Lara Giddings to be dumped.
Senior Labor figures immediately quashed any talk of a leadership challenge, including Infrastructure and Police Minister David O'Byrne, touted as the preferred replacement, who declared his support for Ms Giddings.
Ms Giddings did not front the media yesterday, leaving it up to Deputy Premier Bryan Green to respond to Mr Best's criticisms.
"Really it's up to Brenton to put up or shut up," Mr Green said. "Disunity is death in politics, everybody knows that. That's why I'm saying it's up to Brenton Best really to make up his mind whether or not he's going to campaign for a Labor government leading into the next election. If he's not he ought to think about his position."
However, the ultimatum appears to have had little impact on the Braddon MHA who yesterday vowed to continue to speak out against Ms Giddings and the Labor-Green partnership.
"I don't intend to shut up, I'm dealing with the issues," Mr Best said. "I have been under enormous pressure to not make comments and toe the line, but at the end of the day what I'm saying is right."
Mr Best's public call for a leadership change is the most serious show of ill-discipline since he embarked on his anti- Greens campaign by crossing the floor to vote with the Liberals on a no-confidence motion in Greens leader Nick McKim.
Speaking from Queenstown, Mr Best said he had told Ms Giddings on the phone that she had to stand down and a new leader had to rule out forming a minority government with the Greens again.
He described the conversation as cordial.
"Of course, she doesn't agree."
He is angry over Ms Giddings' recent statements that she would again form a similar arrangement of having two Greens in Cabinet if presented with a hung parliament in March.
"I wasn't asked my opinion on this and I don't think anybody else was either, it was just announced."
In a statement, Ms Giddings said: "Clearly Brenton has to decide whether he wants to be part of a Labor team united behind these objectives or whether he wants to throw rocks from the sidelines, effectively campaigning on Will Hodgman's behalf."