Montreal — Robert Bourassa's election as leader of the Liberal Party in the province of Quebec is Canada's political comeback story of the century. To say that it is the equivalent of Richard Nixon making a return to politics might be overstating things, but not by much.
Mr. Bourassa was leader of the province's Liberal Party from 1970 to 1976, when his personal unpopularity brought down the government in the election that ushered in Rene Levesque and his separatist Parti Quebecois.
Mr. Bourassa's defeat was so complete that he even lost his own seat in Quebec's National Assembly to an unknown poet.
Out in the cold, Mr. Bourassa went to study and lecture in Europe, saying he was studying the federalism of the European Community and how it could be applied to Quebec's problems within the Canadian federation.
In his absence the Quebec Liberals - the provincial wing of the party is separate from the federal party led by Prime Minister Pierre Trudeau - elected an intellectual named Claude Ryan to lead the party. Mr. Ryan could weave fine arguments and score debating points on the editorial page of the newspaper he used to edit, the highbrow Le Devoir, but he could not win an election.
The Parti Quebecois came from behind and won another unexpected victory over the Liberals in 1981. The Liberals started to look for a new leader. And voila, along came the all-new Robert Bourassa.
Mr. Bourassa's convention victory was complete. He received 2,100 of the 2, 800 votes cast at the meeting in Quebec City last month.
Robert Bourassa was in his mid-30s when he first became leader of the Quebec Liberal Party 14 years ago. He was once known as the most unpopular man in Quebec. He is not a charismatic politician, and his Ichabod Crane looks had his critics saying cruelly that he looked like an underfed credit union accountant.
So how did he do it?
For one thing he beat the Parti Quebecois at its own game. The separatist government has made a shambles of the provincial economy. Mr. Bourassa's six years in power now seem like the good old days.
The labor unions that helped bring the separatist party to power are now their archenemies: After six years of free spending the government had to cut back on generous labor contracts.
But perhaps the biggest factor is James Bay, the massive hydroelectric project in northern Quebec. James Bay was Robert Bourassa's idea. When the Parti Quebecois was the opposition, it used to heap abuse on his dream of cheap electricity. That electric power is now one of the few positive things about the Quebec economy. Exports to the United States earn valuable dollars for the Quebec treasury.
The Quebec Liberals under Bourassa are leading the ruling Parti Quebecois in the opinion polls by 42 percent to 19 or 24 percent, depending on which numbers you read. The Parti Quebecois has been a grass-roots party, but it has lost 140, 000 supporters, half its membership, in the past two years.
The Liberals have gained 43,000 members this year alone. Part of the reason for that is that Quebeckers do not want to separate from Canada, and a separate Quebec is the raison d'etre of the Parti Quebecois.
But will they want Robert Bourassa? Gerald Godin, the man who took Bourassa's seat in the 1976 election and is now minister of cultural affairs, said:
''If Quebeckers don't want sovereignty, they also don't want dullness.''
The next provincial election in Quebec is due by 1986 at the latest.