Regardless of who does win tonight, the fate of one leader or the other will be sealed. Abbott has promised to quit if he loses, telling ABC television: "I think one thing we can be absolutely certain of is that I won't be the Opposition Leader after the election."
Rudd's future as Labor leader may be decided by his Brisbane electorate, with some polls predicting he will lose to his Liberal rival. Otherwise, he has sidestepped any commitment: "They are a pretty smart bunch, the Australian people, and they work out fact from fiction, and I will settle with great contentment with their conclusion."
But within Labor there is already speculation of his overthrow. Under party rules that automatically require a new leadership ballot if the Government is defeated, Rudd could be challenged by front-runners such as Education Minister Bill Shorten or Treasurer Chris Bowen - provided he survives in his marginal Sydney seat.
Despite anger at his last-minute switch from former Prime Minister Julia Gillard to Rudd in June's leadership vote, Shorten is widely considered a potential leader as Labor rebuilds.
Yesterday Rudd was swimming against a raging tide. Every major newspaper with the exception of Melbourne's Age - which backed Labor - supported an Abbott victory as most Fairfax publications joined the anti-Rudd Murdoch press in calling for change.
The latest polls tolled further doom. A Galaxy poll in News Ltd newspapers showed voters preferred Abbott as the nation's economic manager and gave a 53-47 per cent lead to the Coalition in the two-party preferred vote that decides Australian elections.
A Morgan poll yesterday put the Coalition's two-party lead at 53.5 to 46.5 per cent, confirming a trend that if translated to a uniform nationwide swing would hand Abbott a majority of as many as 20 seats.
But there are still wild cards. Galaxy found voters were not enthusiastically backing Abbott and were picking what seemed to be the lesser of two evils: only 28 per cent said the Coalition deserved to win, while 44 per cent said Labor deserved to lose.
The widespread disaffection with both Labor and the Coalition has been reflected in a rising number of informal "donkey" votes and a reluctance to either enrol or turn up at polling booths. The Electoral Commission estimates 1.3 million eligible voters failed to enrol, including about a quarter of 18- to 24-year-olds.
The commission has also noted a rising trend of informal votes, reaching a record 5.6 per cent of the total at the 2010 election.
With those who failed to enrol or did not cast a ballot, more than 3 million votes were lost.
About 15 per cent of voters will also make up their minds at the last moment, seen by Rudd as his last big hope.
The ABC's Vote Compass survey of 1.1 million voters found 37 of these were leaning toward Labor and 17 per cent to the Greens.
Rudd and Abbott furiously contested these to the last minute. But given the consistency of the polls and the mood of the nation, Abbott appears certain to emerge the winner.