Rudd's victory over predecessor Julia Gillard triggered a surge back to Labor in polls, but an early election became an increasing priority as support for the Government peaked and Rudd's welcome-back honeymoon began to cool. Polls now place Labor and the Opposition at 50-50, ensuring that the election will be extremely tight and raising the possibility of another hung Parliament.
Yesterday a Galaxy poll said Labor's primary vote was now higher than it was before the 2010 election that led to Gillard's fragile minority Government, with the parties equal in the two-party preferred vote that determines Australian elections. Polls have also consistently shown that Rudd is far more popular than Abbott.
Rudd has further neutralised two of Abbott's major electoral weapons. He has announced the early transition of the unpopular carbon tax to a lower-priced emissions trading scheme, and outmanoeuvred Abbott on asylum seekers. Labor's new policy of transferring all new boat arrivals to Papua New Guinea and Nauru with no hope of ever being allowed entry to Australia has outraged the Greens and refugee advocates. But it has blunted Abbott's "stop the boats" attack - the Opposition will keep the policy if it wins - and polls indicate that Labor is regarded as better able to manage the issue.
Yesterday Victoria's Liberal state Government signed up to Labor's education reforms, with signs that Queensland may join, leaving only Western Australia and the Northern Territory out. Abbott has promised to continue the reforms for at least four years.
The Opposition remains the nation's preferred economic manager, a key advantage in a campaign that will run against the background of a declining economy, rising unemployment, and gloom in the nation's suburbs and boardrooms.
The Coalition will almost certainly win the seats of retiring independents Tony Windsor and Rob Oakeshott, effectively giving Abbott 75 seats requiring only one extra seat to govern. Labor needs to hold all its seats, and pick up others, to continue in power.
Polls indicate it has made significant ground in Queensland and New South Wales - although the impact of last week's corruption findings against former State Labor ministers has yet to be seen.
Abbott will be able to campaign heavily on the cost of living and voters' fears in the marginal seats that will decide the election, with both sides likely to tailor spending promises to local priorities.
Neither side can realistically afford lavish, bit-ticket promises: there is no money in the federal kitty, with falling revenues expected to carve a A$33 billion ($38 billion) hole in the Budget.
The starting gun
The Coalition
* Has a firm hand on 75 seats.
* A uniform swing of 0.5 per cent against Labor produces a Coalition win.
* One more seat means government, two more guarantees an absolute majority in the Lower House.
Labor
* Needs to win seats to retain power and is defending seven seats with margins of 1.5 per cent or less.
* Three seats held by independents in the last Parliament likely to be reclaimed by the Coalition.
* Has 71 seats and has chance of taking back Melbourne from the Greens.
Independents
* Bob Katter and Andrew Wilkie are likely to retain their seats.
Seat held by former Labor MP turned independent Craig Thomson, could be key.
- AAP