Gilles Taillon was elected leader of the Action Démocratique du Québec party on Sunday, squeaking by with just over 50 per cent of the vote.

The 64-year-old ex-teacher and businessman replaces Mario Dumont, who resigned last December on the night of the province's general election.

Taillon captured the crown despite having his leadership campaign sidelined by treatments for prostate cancer. He said he was embracing the victory with humility considering his narrow win against runner-up Eric Caire.

The ADQ is a third-place provincial party that recently came within a whisker of power but now faces an uncertain future.

Taillon's admission of illness prompted Caire to muse that a sick man might not be the best leader for a party in intensive care — a quip that marked the low point of a particularly nasty campaign.

Taillon briefly held an ADQ seat in the legislature and was considered the party's No. 2 figure and only prominent face other than its longtime leader.

Dumont was the boy wonder of the province's politics and already considered a household name by 1994, when he helped to found the ADQ and helped the ragtag political outfit attract mainstream attention. For years, he was the party's only elected member.

Dumont acted as his party's critic on every issue from the economy to the environment and earned news coverage with his seemingly endless supply of quips and one-liners.

The party suddenly began winning ridings after a series of 2002 byelections and came within a handful of seats of dethroning Jean Charest's Liberals in the 2007 provincial election.

The surge of the ADQ excited Conservatives across the country. They saw Dumont as a potential ally in their effort to win the necessary Quebec seats that would give them a majority government.

But those plans quickly crashed and burned.

The Tories' willingness to play political footsie with the ADQ angered Premier Charest and created a deep rift in his relationship with the Harper government.

The Tories' coziness with Dumont backfired when a scorned Charest took shots at them during the last federal election over their cuts to federal culture money. Conservatives saw their Quebec hopes evaporate.

In the meantime, in Quebec City, an Adéquiste caucus full of rookies suffered a disastrous, gaffe-heavy session — its first and only — as the province's official Opposition.

The party was returned to rump status, winning only seven seats in an election last December.

Dumont promptly resigned on election night.