Education Minister Line Beauchamp said she was not resigning from her dual roles because of violence and intimidation related to the student strikes this spring.
Making the announcement at a news conference alongside the premier, Beauchamp said she was actually leaving because she didn't feel like she was helping to solve the problem.
"I am not giving up in the face of vandalism and civil disobedience," said Beauchamp, who will resign her Montreal-area seat.
"I am resigning because I no longer believe I'm part of the solution."
The move leaves Premier Jean Charest with a wafer-thin majority in the legislature — where the Liberals hold 63 seats, the opposition and Independents hold 59, and there are three vacancies.
The new minister is actually the same one Beauchamp succeeded on the education file. Treasury Board President Michelle Courchesne will be adding a second major portfolio, taking on the education job she held from 2007 to 2010.
The treasury-board boss, responsible for keeping government expenses down, made it clear there was no intention to back down on the tuition hikes. While inviting students for continued talks, Courchesne added that the Liberals' university funding plan would be "put in motion."
There was ample evidence Monday that the student unrest, now into its 14th week, would persist.
Night-time protests were planned in Montreal immediately after Beauchamp's announcement. Some said their intention was to celebrate Beauchamp's resignation — while others said they wanted to emphasize that the problem was government policy, not the minister.
Earlier in the day there had been several incidents in and around the city, as protesters blocked the offices of the Ministry of Education on the city's south shore.
There were similar confrontations outside several schools, where protesters were seeking to challenge injunctions allowing classrooms to reopen. Police used chemical irritants and riot gear to break up crowds; one student suffered a head injury.
There were even scuffles outside the Montreal courthouse in which supporters of people accused of smoke-bombing the metro last week tried blocking journalists from grabbing images. They accused the media of being against their cause.
Meanwhile, less than a third of Quebec's post-secondary students remain on strike.
While most students have completed their school year, there remains a committed contingent of protesters — not to mention a chain-reaction of logistical problems around reorganizing the academic calendar after the conflict is resolved.
During her news conference, Beauchamp said she had spoken to student groups about letting a parliamentary committee study the issue of university funding.
She said she asked the students whether they trusted the people's elected representatives to study the question — and that on Monday they had refused.
Beauchamp is the latest of several key figures to resign during this, Charest's third term. An election could be held anytime from this spring to late 2013.
The first question Beauchamp faced at Monday's news conference was whether her resignation actually had more to do with reports about a Liberal fundraising event she attended, in the company of an alleged member of the Italian Mafia — and not the student crisis.
Beauchamp replied that she did not know the person in question. She is the second deputy premier Charest has lost in recent months, after Nathalie Normandeau.
Note to readers: This is a corrected story. An earlier version listed the number of legislature without mentioning three vacancies
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