Are Liberal pollsters Mark Textor and Lynton Crosby a pair of hypocrites? That is the question for the Federal Court.

In the latest twist in a long-running defamation battle, former federal Labor MP Mike Kelly is attempting to prove that the allegation is true and outweighs anything else he may have said about them.

The founders of lobbying firm Crosby Textor are suing Dr Kelly over an October 2011 tweet accusing them of introducing Australia to "push polling", which involves the use of loaded questions to sway the outcome of a poll.

"Always grate [sic] to hear moralizing from Crosby, Textor, Steal & Gnash. The mob who introduced push polling to Aus," Dr Kelly wrote using his official MP Twitter account.

Mr Textor and Mr Crosby complain the tweet conveys that they "introduced to Australia the morally disreputable practice of pretending to conduct a genuine and objective opinion poll" while doing quite the opposite.

But Dr Kelly's high-powered legal team, including defamation guru Bruce McClintock, SC, argue the tweet suggests something even worse: the two men are hypocrites.

On Wednesday, Justice Steven Rares agreed this was a possible reading. He said the tweet was capable of conveying the allegation that the Liberal pollsters were hypocrites, meaning they "expressed moral views about matters that were different from what they actually did".

It will be determined at trial whether this is worse than introducing Australia to morally dubious polling practices.

Under a defence known as "contextual truth", a person accused of defamation can argue their publication conveyed an allegation even more damaging to the plaintiff's reputation than anything the plaintiff has pleaded.

If the defendant can prove the more damaging allegation is true, the plaintiff loses the case because any other allegations could not further harm their reputation.

Justice Rares ruled that Dr Kelly should redraft his defence to support the allegation that both men are hypocrites.

He was ordered to pay half of Mr Textor and Mr Crosby's costs of the preliminary battle. The ALP has contributed $20,000 to his defence.

The case is set to become the first Twitter defamation battle in Australia to proceed to a full trial. Prominent columnist and author Marieke Hardy settled a defamation case in 2011 after she erroneously ''named and shamed'' a Melbourne man on Twitter as the author of a hate blog directed at her.