Labor continues to apply pressure on Prime Minister Scott Morrison to explain why hundreds of millions of dollars were spent building car parks in coalition seats, which is being described as an industrial scale rort.
A scathing auditor-general's report has found the $660 million coalition scheme was not effective or merit-based.
Not one of the 47 commuter car park sites promised by the coalition at the 2019 election was selected by the infrastructure department.
Labor spokesman for cities and urban infrastructure Andrew Giles said the damning report points directly to the involvement of the prime minister and his office, in a troubling echo of sports rorts.
"Now that Scott Morrison has emerged from his stay at the Lodge, he must take responsibility for the train-wreck that is his car park rorts scandal," Mr Giles said in a statement on Sunday.
Mr Morrison completed 14 days of isolation after his official trip to Europe last Thursday.
His ministers continue to defend the scheme.
"We are going to continue to deliver infrastructure projects for the nation because they lift our national productivity," Finance Minister Simon Birmingham told ABC's Insiders program on Sunday.
"The Australian people had their chance and voted the government back in the last election and we are determined to get on and deliver those election promises that we made in relation to local local infrastructure."