Both major parties have already splurged more than $6.5 million on TV advertising in the past eight weeks (Liberals $3,747,121, Labor $2,827,807).
Labor has emailed supporters asking for donations to make up its $13K short fall in advertising targets to get "The Least Negative Ad Ever" on TV on Wednesday.
"In the final 72 hours of this election, a quarter of voters will make up their mind. So together we can blast this contest wide open," assistant national secretary Paul Erickson urged supporters on Tuesday.
The party has raised enough to get the ad on daytime pay TV, and hopes to raise enough to get it on during more expensive prime time.
Labor is buying up TV ads at a cost of between $5,000 and $10,000 a pop, while the Liberal party is splurging thousands on cheaper FM radio ads.