Peter Whish-Wilson believes Assange is a political prisoner and is unlikely to survive a US trial due to his waning health.

He highlighted comments from UN rapporteur on torture Nils Melzer who said Assange would face a "show trial" if extradited to the US.

Mr Melzer says Assange's case has ramifications further than one individual's future, and is about the battle over press freedom and the future of democracy.

Senator Whish-Wilson asked Foreign Minister Marise Payne in parliament why she flew to Thailand to lobby against the extradition of Australian soccer player Hakeem al-Araibi to Bahrain.

"Given that you and your government were so vocal about Hakeem's detention and the risks of his potential extradition, why have you not shown the same zeal and commitment to secure the release of Australian citizen and Walkley-Award-winning journalist Julian Assange?" he asked.

Senator Payne says the cases had different circumstances, but she was in regular contact with United Kingdom authorities and had been assured Assange was held in appropriate and humane conditions.

"The Australian government has no standing in any of Mr Assange's legal proceedings and is unable to intervene in them," she said.

Senator Whish-Wilson plans on travelling to the US to directly appeal to officials to drop the charges before the extradition hearings continue in May.

"I am seriously considering going to the US and doing a lobbying trip there, meeting the Democrats and others, and even some Republicans," he told reporters.

"I'm not asking anyone else to go with me, but I do believe that there is opportunity for us to go straight to the lion's den."

He was unable to travel to London earlier in February with Nationals MP George Christensen and independent Andrew Wilkie, who visited Assange at Belmarsh prison.

The charges Assange faces in the US carry a total of 175 years' imprisonment.

Australian Associated Press