Australians yesterday started an historic convention to decide if they should replace the British monarch as head of state with a president, possibly along Irish lines.Late in the last century the fledgling colonies of New South Wales and other states were fighting as to whether to federate and form a nation. They did. This time the argument is over whether to dump the constitutional monarchy and replace it with a republic.The pro-republic feeling has been brewing for more than 20 years since Queen Elizabeth's representative in Australia, the Governor-General, sacked a Labor Party prime minister. Her Majesty was not involved in the dismissal of Mr Gough Whitlam, but the outrage in Australia was intense and long lasting.Now 152 delegates, half of whom were elected by a postal ballot and half appointed by the federal government, have two weeks to come up with a clearconsensus for constitutional change. Their model for the type and timing of a republic will go to the people in a referendum during 1999.The Prime Minister, Mr John Howard, who is against changing the system, announced yesterday it was possible a president could be installed in time for the centenary of federation celebrations in 2001."I oppose Australia becoming a republic because I do not believe that the alternatives so far canvassed will deliver a better system of government than the one we currently have," he told the opening session in the country's former parliament house in the capital, Canberra."I go further: some will deliver a worse outcome and gravely weaken our system of government. I believe that modern government is most workable where the essentially ceremonial functions of government are separated from the day-to-day executive responsibilities," Mr Howard said.Many republicans are determined to appoint an Australian as president in time for Sydney 2000 Olympic Games; but there are problems, especially because the republicans are so bitterly divided about just what sort of republic they want.The key Australian Republic Movement (ARM) supports a minimal change it believes it can get passed by a referendum, which must be carried by a majority of Australians and a majority of the six states. But breakaway republican groups want to use the opportunity to forge a much more ambitious reform, such as reconciliation with Aboriginal people and having a bill of rights.The biggest split is on how the president might be elected. ARM and the Labor Party want their new head of state elected by a joint sitting of parliament. But many of the breakaway groups, and according to polls most Australians, want the people to decide as in Ireland or the US.The Labour opposition leader, Mr Kim Beazley, said the convention was now finishing off the job started by the founding fathers in the last century. He said the nomination of a president by the prime minister and cabinet followed by a parliamentary election was the only way. "Our view is that this method of election causes the minimum possible disruption to current constitutional arrangements," he said. "It is the model most likely to produce a non-partisan figure, and as such, the breadth of public support a head of state must enjoy."A poll out today showed a slim majority of Australians now support a republic but lower levels of support in the smaller states, such as Tasmania, mean the fate of any referendum is far from certain. It showed 52 per cent of respondents now favour an Australian head of state, compared with 37 per cent support for the monarchy. Eleven per cent were undecided.The republicans have the majority of delegates at the convention so the monarchists' strategy is to accept the inevitable that there will be a consensus on one republican model and focus on making sure the referendum rejects it. Mr Lloyd Waddy, of the Australians for a Constitutional Monarchy group, said there would be no compromises with the republicans as their whole argument was flawed. He said Australia was totally independent from the UK and had an Australian head of state in the shape of the Governor-General.