Political advertising on television and radio stopped from midnight Wednesday as the media blackout came into place, but online users won't be immune from political messages from parties.
Prime Minister Kevin Rudd said Labor would continue pressing voters with political messages on Facebook after the ban comes into place, in an email to supporters on Wednesday.
Labor is expected to use online advertising to respond to the Coalition’s full costings announcement, which won't be released until Thursday afternoon.
Associate Professor Sally Young of the University of Melbourne says online advertising falls outside the boundaries of the traditional electronic media blackout, and there's nothing to stop other parties following suit.
"It doesn't break the rules because the rules apply to electronic media," but she says it does break the "spirit" of the blackout, which was designed to give voters "a period of quiet reflection" before polling day.
She added the media blackout is "probably not" relevant in the current media landscape.
"We used to have rules that you couldn't even report news in the last days of the election campaign," she said. "So times move, times change."
However, warns Young, advertising on Facebook is not an ideal method for Labor, where it will be harder to target the swinging voters in marginal seats they'll need to convince in order to gain traction at the polls.
"[Political parties] still prefer TV advertising and direct mail," she says. "There's only so much they can do in terms of reaching their target voters."
Minor parties and action groups are among those benefitting from the rise of online advertising, because of the quick, easy way it can be used to reach voters.
"They don't have the money to spend on television advertising," she says. "For them, there is no choice really."
The media blackout is legislated under Schedule 2 of the Broadcasting Services Act 1992, which is administered by the Australian Communications and Media Authority (ACMA).
It begins at midnight on the Wednesday before polling day.
