Zimbabwe's ruling Zanu-PF party has backed a move to extend the mandate of President Robert Mugabe by two years.
Robert Mugabe is in his sixth term as president
The annual party conference approved a plan to postpone the next presidential election - when Mr Mugabe has said he will retire - from 2008 to 2010.
Delegates said there should be no debate on succeeding the president, because there were no vacancies.
Zimbabwe has the world's lowest life expectancy, highest inflation rate and chronic unemployment.
Mr Mugabe's critics say he has ruined what was one of Africa's most developed economies.
The president says he is the victim of a Western plot to bring him down because of opposition to his seizure of white-owned land.
Following last year's parliamentary elections, Zanu-PF has a two-thirds majority, enabling it to change the constitution.
Mr Mugabe has been president since Zimbabwe became independent in 1980.
BBC Southern Africa correspondent Peter Biles says that behind the scenes there is serious in-fighting within Zanu-PF, and no clear decision about who should succeed Mr Mugabe.
That is partly why the issue has been shelved until 2010, our correspondent adds.
Thousands of delegates cheered as a party official read the resolution on the controversial issue, which said:
"We want to reaffirm the leadership of President RG Mugabe [...] and thus resolved that there should be no debate on succession because there are no vacancies."
The proposal still has to go to the party's central committee and to parliament, and there is some opposition within the party to the move which could grow.
Although Zanu-PF describes the constitutional changes as an effort to achieve "harmony" in the election process, critics say the move is really about Mr Mugabe holding on to power.
"He basically has decided to succeed himself," independent MP Jonathan Moyo told the BBC.
But Information Minister Paul Mangwana said Mr Mugabe was a "democrat".
"If the people want him, let him remain in power," he said.
Mr Mangwana also denied that Mr Mugabe was too old to continue to run Zimbabwe: "He's agile, he's lucid, he has a clean bill of health."
But the Catholic Archbishop of Bulawayo, Pius Ncube - one of President Mugabe's strongest critics - says he is obsessed with clinging on to power.
"On the one side, you remember he was saying he would retire at 78. Now he's approaching 83. He keeps changing his goalposts. 'this is my last time, this is my last time'.