"Winnability" usually drives a political leadership race, but in this case Liberals picked the dark horse. The one with the least charisma. The candidate haunted by polls showing him as least likely of the top contenders to return his party to power.

But the delegates picked someone they could trust. The one with the most experience in Ottawa's halls of power. A friend, a respected colleague, a well-known former cabinet minister who had proved himself, time and again, on difficult files.

"Files" is one of those words associated with Stephane Dion -- implying hard work, a studious approach, a methodical and legalistic approach to difficult problems.

This tightly-wound former academic worked his way up in politics, over the past decade, just as he worked his way up the balloting during the Liberal leadership convention this weekend. Slow and steady wins the race.

The son of Leon Dion, a famed constitutional scholar, he was recruited into politics by a couple of heavyweights in the Liberal establishment. After the near-loss for federalists in the 1995 Quebec referendum, they needed a new voice on their national unity file.

Aline Chretien told her husband Jean, so the story goes, to make a phone call to the young man defending the federalist option in Quebec on TV. When Dion, then 40, arrived for his meeting on Parliament Hill, he came off the bus with a backpack and a bandana. Jean Chretien was skeptical of the image, but open to young man's ideas.

Chretien and Dion are said to be still close, and apparently went fishing together last summer.

The former PM showed up at the Liberal leadership convention on Friday, and in criticizing the Conservative government's recent motion recognizing the Quebecois as a nation within a united Canada, offered a little hint of his support to Dion.

Chretien said he found Prime Minister Stephen Harper's motion confusing and that he's always liked "clarity." The Chretien government, of course, brought in the Clarity Act to set the terms of secession. Dion was the architect of that act.

Dion won a seat in the House of Commons in a 1996 byelection, and soon became Chretien's minister of Intergovernmental Affairs. He worked the file, and led the series of "clarification initiatives" that resulted in the Supreme Court of Canada's opinion on Quebec secession, 1998, and the Clarity Act, which was passed by the House of Commons on March 15, 2000.

His determined defence of Canadian unity -- particularly, with an aggressive letter-writing campaign -- won him plenty of ridicule in Quebec. He was depicted in editorial cartoons as a rat. But he managed to keep winning back his seat. And, briefly turfed out of Cabinet in the early days of the Paul Martin government, he later returned as minister of environment and won more accolades for his work on the Kyoto file.

And what about those negatives? Things change -- Liberals thought they'd picked a winner with Paul Martin in 2003, but he seemed to become a different man, with the pressures of the top job.

Dion may have his own transformation, in the top job. He says his English is improving as he's travelled across this country for almost a year in this leadership campaign. And perhaps at home, Quebecers will form a new impression of Dion once he starts as Opposition Leader.

Brian Tobin says Dion is appealing to people in the party because "people want to move away from recent history. They want a change not just in a leader but in leadership, want renewal and I think we're getting that in Stephane Dion in spades," he told CTV News.

When Dion told Lisa LaFlamme earlier this week why he was running for the leadership, he sounded determined, in that methodical way. He sounded like he was looking forward to more files, bigger files.

"Because I don't think it will be done as well as I want if it wasn't me. That's always been my motivation in politics."