The chief adviser on senate matters says Lidia Thorpe is eligible to be a senator despite her claim she pledged allegiance to Queen Elizabeth's "hairs" when she was sworn in to parliament.

Clerk of the Senate Richard Pye, who is the main adviser to the senate president on proceedings, said on Monday there was no "test of sincerity" when asked about Senator Thorpe's swearing-in ceremony.

"The idea that we would think that perhaps there's not due reverence or due regard being had to this constitutional requirement should somehow interfere with the ability of a democratically elected Senate to continue taking their part in the Senate, takes the point a bit too far," Mr Pye told senate estimates.

He confirmed Senator Thorpe would have pledged allegiance by signing her oath anyway, as legal experts and other parliamentarians have pointed out.

"In this case, the words that were spoken are the same words that appear in the test role," he said.

"Senator Thorpe by signing them was attesting to the fact that those were the words that she had spoken.

"And the President countersigned it to say that the oath, the affirmation has been properly made and subscribed before her."

Senator Thorpe was forced to walk back her claim that she did not say her senatorial oath correctly after it sparked questions around her eligibility.

She instead said that she misspoke.

The Greens-turned-independent made the claim after her expletive-ridden protest during the royal visit last month.

Joseph Olbrycht-Palmer - NCA NewsWire