Tasmanian senator Tammy Tyrrell has announced she is resigning from the Jacqui Lambie Network and will sit on the crossbench as an independent.
In a statement, Senator Tyrrell said she had not been kicked out of the party, but Senator Lambie had suggested she go her own way.
"Jacqui has indicated she is not happy with the way I have been representing the Jacqui Lambie Network," she said.
"I am not doing this because I want to harm Jacqui or the Network. I want to see Jacqui and the JLN continue to succeed.
"As it is now clear that the Network does not have confidence in my ability to contribute to that success, I do not wish to do anything in my advocacy for Tasmania that might harm it."
Senator Tyrrell was elected to the Senate in 2022 after serving as Senator Lambie's office manager.
She said it was a "tough decision" but added there are "no hard feelings between Jacqui and I".
"I am hopeful that this is the right decision for Jacqui, the Network and the people of Tasmania," she said.
The JLN picked up two seats, with the possibility of winning three, at the recent Tasmanian state election, with the new members likely to play a significant balance of power role in the new parliament.
Senator Tyrrell wasn't visible during the state election campaign and did not attend the party's function on election night.
Senator Lambie was first elected to federal parliament in 2014 as part of the Palmer United Party, before sensationally quitting the party shortly after.
Senator Lambie was questioned during the state election campaign on the risk of having people elected under someone else's name, to which she responded: "I just hope and pray that I have picked the right people".
During the 2022 election campaign, Ms Tyrrell said she and Senator Lambie "are always going to be united."
"You don't stick with someone that long if you are not a believer in the message and the good she is doing for the state," Ms Tyrrell said in 2022.
"We may have a different flavour, a different perspective, we may take a different street, but we always come back with what is going to be best for people here in Tassie."
In her first speech to parliament, Senator Tyrrell said: "I didn't get here because of Jacqui. We got here together. And I love her to bits. Because we're a team."
Election analyst Kevin Bonham said it was another example of minor parties being unstable in the Senate, and flagged it could now be an issue in the Tasmanian parliament.
"It is symptomatic of the problem that these parties have holding themselves together," he said.
"That problem is going to be extra strained by the fact that the new Lambie members in the Tasmanian parliament are going to be thrust into a position of great power and a lot of instability."
Senator Tyrrell joins senators Lidia Thorpe and David Van on the crossbench as independents, who both also quit their parties during their terms.
Senator Lambie has been contacted for comment.