The Victorian Electoral Commission on Wednesday sent its probe into Matthew Guy and his former chief of staff Mitch Catlin to the Independent Broad-based Anti-Corruption Commission for further investigation.
Electoral commissioner Warwick Gately said his organisation had exhausted its own attempts to inquire into what may be a breach of Victoria's funding and disclosure laws under the Electoral Act.
"We became aware of suggestions Mr Catlin was alleged to have tried to circumvent donation disclosure laws," he said in a statement on Thursday.
"It's my responsibility to ensure compliance with all electoral laws and ensure all participants are held to the same standard."
Mr Catlin resigned in August after it was revealed he allegedly asked a billionaire Liberal donor to make more than $100,000 in payments to his private marketing company.
A contract for the proposed arrangement was sent to Mr Guy's personal email address but he has categorically denied it was signed or agreed.
Mr Guy has repeatedly said he and the Liberal Party have fully co-operated with the electoral commission and denied exploiting a legal loophole to stymie the probe.
"I've done nothing wrong," he told reporters at Morwell on Thursday.
"I provided everything that was asked to me. I've done that once, I'll do that again if need be."
But the electoral commission said it had not received full co-operation from those involved "despite public statements to the contrary".
It also said while it is not in a position to allege wrongdoing based on the allegations, the possibility of offences has not been able to be discounted.
Mr Guy pointed to the statement's note on the VEC making no allegation of wrongdoing before slamming the Labor government's own multiple corruption investigations.
Premier Daniel Andrews' government is subject of another anti-corruption commission inquiry over the awarding of two grants worth $3.4 million to a union on the eve of the 2018 election, despite objections from health department officials.
Since first elected in 2014, the Andrews government and Labor have been the focus of repeated integrity inquiries over branch-stacking schemes and misusing taxpayer funds.
The Liberals themselves will refer the issue of group ticket voting and deals done by so-called "preference whisperer" Glenn Druery to the corruption watchdog after recordings were leaked.
A covert video exposing the backroom preference dealings was sent by the Angry Victorians Party to the Herald Sun.
In the footage, Mr Druery offers his services to get candidates elected as part of the state's group voting ticket system.
Victoria is the only Australian jurisdiction with the system, which allows parties to distribute upper-house preferences when people vote above the line.
Party officials said they were first contacted by Mr Druery in May and feigned interest to join his system, collecting recordings of him explaining his method and asking for $55,000 for each candidate elected at the November 26 poll.
He boasted Labor was happy with his operation because it led to the Greens losing seats in 2018.
Mr Andrews said the recordings were concerning but would not commit to reform.
Victorian parliament's electoral matters committee, which conducts a review after every election, may look at whether upper house reforms are needed, he said.
Mr Guy vowed to fix the system, saying people buying their way into parliament was akin to a third-world democracy.
Meanwhile, three teal independent candidates will be allowed to use their preferred how-to-vote cards after the VEC's decision was struck out.
The Victorian Civil and Administration Tribunal found the cards were not misleading to voters, as claimed by the commission.