Jacqui Lambie says she is seeking urgent advice on whether the man who is due to replace her in the Senate is eligible to do so.
Devonport mayor Steve Martin was cleared by the High Court to replace Ms Lambie, who resigned over her dual citizenship.
The court found Mr Martin's local government job was not a block to him being in federal parliament.
However, Ms Lambie said Mr Martin was sacked from the Jacqui Lambie Network at a party management committee meeting this week.
"Steve is no longer in the party - it's in black and white," she told AAP on Thursday.
"He should not be sworn in as a senator."
Ms Lambie said because Mr Martin was not a party member he could not fill a position vacated by her party.
High Court judge Geoffrey Nettle is due to formally order Mr Martin's election at a hearing in Melbourne on Friday morning.
He is then expected to be sworn into the Senate in Canberra on Monday, alongside Liberal senator-elect Richard Colbeck.
Ms Lambie said her case was almost identical to that of former Nick Xenophon Team senator Skye Kakoschke-Moore, which was due before the court next week.
In that case Ms Kakoschke-Moore, who also quit after discovering dual citizenship, wanted to replace herself in the Senate, arguing the person who was expected to replace her, Tim Storer, was no longer a member of the NXT.
"I want to seek what happens with the Skye Kakoschke-Moore case," Ms Lambie said.
Mr Martin was surprised on Wednesday night to learn of his expulsion from the party through an open letter from his former running mate.