Queensland Labor MP Rob Pyne has quit the Palaszczuk Government, loosening its grip on power.
Labor and the Liberal National Party now hold 42 seats each in the 89-seat house.
ALP state secretary Evan Moorhead confirmed the resignation.
“I haven’t received a letter but I understand that he has resigned, yes,” Mr Moorehead said.
“I am sure we will find out more tomorrow.”
Mr Pyne earlier on Monday tweeted that it was the “hardest day of my political life”.
The first-time MP quit the left faction earlier this year.
He spoke out against what he called a lack of reform agenda, including a failure to act on coal seam gas, the powerful mining lobby, official corruption and a women’s right to chose an abortion.