Executive director of the ANAO Brian Boyd speaking this morning (Image: Lukas Coch/AAP)

It started with a list of the top 20 marginal seats, cooked up in former infrastructure minister Alan Tudge's office. It ended with the Coalition funnelling millions meant to fund commuter car parks towards projects in Coalition-held electorates or target seats in the run-up to the 2019 election.

At a spillover estimates hearing of the Senate's Rural and Regional Affairs and Transport Legislation Committee this morning, officials from the Australian National Audit Office (ANAO) revealed the startling lack of transparency and effective administration, as well as bad design that plagued the $660 million commuter car park fund, and its parent program the $4 billion Urban Congestion Fund (UCF).

The rort went something like this: in September 2018, weeks after Scott Morrison became prime minister, staffers in Tudge's office put together a list of the 20 most marginal electorates in the country. This was long before the government decided to focus on car parks. Instead, funding under the entire UCF began with a list of electorates.