Treasurer Josh Frydenberg is facing two court challenges to his election win, after questions were raised about his citizenship and the Liberal Party's campaign conduct.
Oliver Yates, who unsuccessfully contested the Victorian seat of Kooyong against Mr Frydenberg, has lodged documents with High Court sitting as the Court of Disputed Returns.
A Kooyong resident Michael Staindl also filed a court petition on Wednesday arguing Mr Frydenberg should be disqualified under the constitution because he is entitled to Hungarian citizenship.
Mr Yates argues the Kooyong election was "affected by illegal conduct committed by the Liberal Party, to the knowledge of both Liberal candidates, on the day of the election".
The alleged illegality was conduct that was likely to mislead or deceive voters in relation to the casting of their vote.
Federal Treasurer Josh Frydenberg earlier this month. Source: AAP
The Liberals authorised a sign displayed at Kooyong polling booths on election day, with three features: it was in the Australian Electoral Commission's official colours of purple and white; it had no Liberal branding and did not refer to the Liberal candidates or policies; and it was in Chinese language.
The translation of the words was: "The right way to vote: On the green ballot paper fill in 1 next to the candidate of Liberal Party and fill in the numbers from smallest to largest in the rest of the boxes".
On election day, the AEC said it would not take action because the signs were authorised, and there were no rules around colour schemes.
The same argument over the signage is being put by retired social worker and climate campaigner Leslie Hall in her challenge to the election of Gladys Liu in Chisholm.
Both electorates are home to large populations of Chinese speaking and ethnically Chinese voters.
Ms Hall said she had serious concerns about the "erosion of democracy" in Australia and overseas.
"I am concerned that the AEC allows deliberately misleading statements in a foreign language to be provided to people who may not have access to English and therefore to a full understanding of the electoral processes," she said in a statement on Wednesday.
Lawyer Michael Bradley, managing partner of Marque Lawyers, said the Liberal Party went too far in Chisholm and Kooyong.
Liberal MP Gladys Liu on the campaign trail. Source: AAP
"It posted signs that were clearly designed to trick Chinese speaking voters into thinking that the AEC was directing them to vote in a particular way. That is just not on," he said.
"Neither of our clients is motivated by politics in bringing their case forward, but by their belief that the slide towards anti-democratic and dishonest behaviour in our electoral process needs to be stopped before it gets even worse.
"We will be asking the court to hear both petitions and provide some much-needed clarification for everyone on where the limits of acceptable campaign conduct lie."
Labor acting national secretary Paul Erickson said the party believed there was a strong case the signage breached electoral laws.
"But the significant cost and protracted nature of a legal challenge means we will not be seeking to overturn the outcome through legal action in the Court of Disputed Returns."
Mr Frydenberg's mother, who arrived in Australia in 1950, was born in Hungary in 1943.
But he denies holding citizenship by descent, citing expert advice.
