Votes are being counted in Australia's most populous eastern states, after Saturday's federal elections.
Howard began the day with a walk by Sydney Harbour
Polls have now closed everywhere except Western Australia, where they will stay open until 1000GMT.
Prime Minister John Howard and his main rival, Labor party leader Mark Latham, largely focused on domestic issues during the election campaign.
But the subject which the two candidates differed on most was the US-led war in Iraq.
John Howard's conservative government has vowed to keep Australia's 850 troops in the Gulf indefinitely. Mark Latham said he would withdraw them by Christmas.
Opinion polls before the vote predicted Mr Howard was slightly ahead of Mr Latham, and early results put him on course for a fourth consecutive term in office.
Electorate of 13 million
Polls open at 0800 local time in each state (there are four time zones)
Two main contenders: John Howard's Liberal/National coalition and Mark Latham's Labor Party
Greens Party is the largest minority group
Voting is compulsory
Mr Howard's Liberal-National coalition has so far taken an early lead in the island state of Tasmania, where polls closed first.
All five Tasmanian lower house
seats are currently held by the Labor Party, but computer projections by the Australian Broadcasting Corporation show two of those seats are in danger of falling to the conservative coalition.
Analysts say this is because the government has taken a less hard-line stance than Labor over logging in the area.
The loss of two seats in Tasmania would mean Labor needs to win an additional 15 seats on mainland Australia to beat the conservatives.
Mr Howard's Liberal-National coalition controlled the outgoing
parliament with 82 seats, while Labor had 64 seats. The rest of the seats were taken up by minority parties or independents.
Mr Howard voted on Saturday in the Sydney suburb of Bennelong, where he faced a handful of demonstrators shouting "Liar, liar".
But there were also supporters there to greet him.
Mr Howard had predicted a tight vote.
Latham won a raffle, but can he win the country?
"I've got a few butterflies, why wouldn't you on a day like
this?" he said, as he made his to way to vote.
Mr Latham also voted in Sydney, and he won a meat tray in a local raffle while on the way to vote.
"It's good to be a winner at 1030 on Saturday," he joked.
Voting in Australia is compulsory, and many schools take advantage of the fact that polling stations are operating there to run fundraising coffee stalls and other activities.
In a flurry of last-minute radio interviews on Friday, Mr Howard urged Australians not to vote out a government which had given their country the strongest economy since World War II.
He urged voters to stick by him, even if they disagreed with some of his past decisions.
"I again say to undecided voters who might want to give the government a kick but also want to see the government returned... not only do kicks hurt but if there are enough of them, they will tip a government out," Mr Howard said.
Mark Latham also hit the airwaves with his last-minute pitch, managing a total of 12 interviews on Friday.
All 150 seats in the House of Representatives up for grabs
Voters rank all candidates in terms of preference, beginning with 1 for their favourite candidate
Candidates with the smallest number of 1 votes are eliminated, and the voter's number 2 preference is counted instead. The process continues until there is a winner
Voters will also chose half the 76-member Senate seats
Senate votes are counted on a proportional representation system
He attempted to quash accusations that he is too young and inexperienced for the job of prime minister, compared to 65-year-old Mr Howard - a political veteran.
"I think at age 43, I can take the country forward 30 years, more so than the prime minister who's not able to give a commitment even about the next three years, let alone 30," he said.
But he also managed to keep his sense of humour, saying of Mr Howard: "I hope he has a good day [on Saturday] but not as good as mine," he said.
Both candidates have made the economy a central issue to their campaigns, vowing to keep interest rates low and the budget in surplus.
Health care, education and the environment have also been key issues.
But the issue which has gained most international attention is the war on Iraq, with many commentators seeing the Australian election as the first referendum for the three leaders who launched the March 2003 invasion.
The other two leaders, US President George Bush and UK Prime Minister Tony Blair, face elections in the near future.