A by-election in the Cook Islands' Areora-Tengatangi-Ngatiarua electorate will be held on 18 March after Te-Hani Brown confirmed she has left the Democratic Party.
Ms Brown won the seat in last year's election, but last month decided to defect to the Cook Islands Party-led coalition government to give it a majority.
The Cook Islands News reported she now plans to stand as an independent candidate in the by-election.
In a statement yesterday Ms Brown said she advised the Speaker of the Parliament, Niki Rattle, as well as the president of the Democratic Party Sean Willis, about her resignation as the MP for the seat "effective immediately".
Ms Rattle confirmed she had recieved Ms Brown's resignation.
Brown said she intend to contest the upcoming by-election as an independent candidate so that she could continue to represent her people in her constituency and freely support the government of the day.
"I believe that I am doing the right thing in handing the seat back to the people who voted me in - who also supported and influenced this decision - allowing them the right to reinstate me as an independent member that can continue to be their voice in Parliament," she said.
"I look forward to continuing my work as an MP so that I can continue helping our people of Enuamanu, and support the government with the completion of our projects."