Lambie refers Palmer's legal threat to Senate officials

Former Palmer United Party senator Jacqui Lambie has asked the Senate's most senior official to investigate Clive Palmer's $2 million legal threat.

PUP is planning to sue Senator Lambie, and fellow independent Glenn Lazarus, after the pair separately quit the party and remained as independents in the upper house.

Mr Palmer claims Senator Lambie owes the party about $2 million for her election in Tasmania and Senator Lazarus should hand over $7 million for his Queensland seat campaign in 2013.

Senator Lambie is taking the threat seriously and referred the matter to her legal team and the Clerk of the Senate, Rosemary Laing.

Senate rules prohibit anyone interfering with the free and fair performance of a senator but Mr Palmer claims he's not trying to influence their votes.

The senators promised to represent PUP for the six-year Senate term if elected, he said.

"People just don't like being lied to," Mr Palmer told Fairfax radio on Wednesday.

"Thousands of people worked for them ... so it's only fair that they should repay the money that people spent on them."

Mr Palmer's companies provided the bulk of the $28 million to PUP and declared it to the electoral commission.

He's prepared to fork more than $3 million for the court cases, a figure it's unlikely the pair could match.

Senator Lambie was elected on 1500 personal votes, while Senator Lazarus received about 6000. Mr Palmer believes his $9 million got them across the line.

However, PUP ran 33 candidates in Queensland and seven in Tasmania. PUP's campaigning in Queensland also got Mr Palmer elected in the lower house.

Suing the pair won't get PUP back the balance of power in the Senate - where it now only controls one vote - but Mr Palmer says they wouldn't be allowed back into the party anyway.

Comment has been sought from Senator Lazarus.