OTTAWA -- History shows that even with one foot out the door, Prime Minister Jean Chrétien still has a firm enough grip on power to govern effectively for the next 18 months, one of Canada's longest-serving bureaucrats said yesterday.

"I don't think he's a lame duck at all," said Gordon Robertson, a former clerk of the Privy Council.

Mr. Robertson worked with prime ministers Mackenzie King, Louis St. Laurent, Lester Pearson and Pierre Trudeau. He said Mr. King served as prime minister for almost a year after announcing his departure without seeing his government disintegrate or facing internal revolts.

Mr. Trudeau announced before the 1980 election that he would not run again, and still lasted a full mandate, all the while patriating the Constitution. As he showed toward the end of his mandate, Mr. Trudeau still had access to political posts to reward his supporters.

Mr. Pearson had a tough time governing in his last months as Liberal leader in 1967 and 1968, after he had announced his resignation. At one point, Mr. Pearson's government lost a budget vote when too many leadership candidates were out campaigning to replace him.

But Mr. Robertson said the Pearson government, working without the benefit of a majority, never achieved a high level of cohesion anyway.

Mr. Chrétien, who has already laid out his agenda for the rest of his tenure, has a lot of power to achieve his goals, Mr. Robertson said.

"Far from others trying to trip him up and not co-operate, there would be a feeling of obligation in the opposite direction. Here is somebody who has laid out a reasonable plan, has said what he wants to do, and I suspect the reaction will be he ought to be supported," said Mr. Robertson, who had been urging the Prime Minister to announce a resignation date.

Mitchell Sharp, Mr. Chrétien's long-time adviser, said Liberal MPs still have to behave while the Prime Minister implements his program.

"If the rest of the members of Parliament have any forward views, they ought to be careful about how they deal with him, because it wouldn't help them if they aroused antagonism in the Prime Minister," Mr. Sharp said.

For now, with the opposition at its heels, the federal government has 18 months to deal with Mr. Chrétien's ambitious agenda: dealing with child poverty, health, the environment, aboriginals, urban infrastructure and ethics.

None of these issues comes with quick and easy fixes.

And through them all, the Liberal Party risks descending into renewed infighting, one of the biggest tests facing Mr. Chrétien.