"You might have some persuading to do," he said.

The court heard Senator Hanson-Young intended to call five senators, including Senator Keneally, to give evidence in the five-day trial in Sydney.

Senator Keneally is a key figure in Opposition Leader Bill Shorten's campaign for the prime ministership. The former NSW premier and TV presenter is expected to be promoted into cabinet, should Labor win the May 18 poll.

Mr Leyonhjelm, a former Liberal Democratic Party Senator who lost his bid for a NSW upper house seat in the March state election, intends to call Senators Derryn Hinch and Stirling Griff to give evidence. Both men had previously declined to cooperate with Mr Leyonhjelm's lawyers.

Loading

Senator Hanson-Young is not suing over Mr Leyonhjelm's comments in Parliament – which are covered by parliamentary privilege – but their repetition and expansion outside the Senate to Sky News' Outsiders program, the ABC's 7.30 program and Melbourne radio station 3AW, paired with a media statement posted on blogging website Medium.com.

Senator Leyonhjelm has said his "stop shagging men" comment in the Senate in June last year was in response to an alleged claim by Senator Hanson-Young that "all men are rapists". She denies making that claim.

In a statement of claim, lawyers for the Greens senator argue Senator Leyonhjelm defamed her by suggesting she made that "absurd" claim in Parliament.

They also say his comments paint her as a "hypocrite" in that she "claimed that all men are rapists but nevertheless had sexual relations with them", and a "misandrist, in that she publicly claimed that all men are rapists".

Senators Keneally, Hinch and Griff, among others, are expected to be asked what they heard during the Senate debate last year.