After more than nine years of Liberal government, opposition parties say that years of ethics controversies and months of student conflict are finally taking their toll.
But few in Quebec would have predicted a Liberal defeat in either of the ridings up for grabs on Monday night. Not only were they both Liberal bastions (the party held on to one of them) but polls also suggested the party entered the byelection with public support for its tuition-hike policy.
Just how shocking was the loss? The riding name became a top trending topic in Montreal on Twitter through much of Tuesday — a sharp break from the usual indifference that greets byelection results.
The Parti Quebecois won in Argenteuil, a riding just north of Montreal, with 36.2 per cent of the vote, compared to 33.4 per cent for the Liberals. The Liberals easily held their Montreal fortress of Lafontaine, although by a smaller margin than in the past.
It was an energizing result for PQ members, who entered their caucus meeting in Quebec City on Tuesday chanting "Liberals, out the door."
PQ Leader Pauline Marois and her caucus have taken to wearing the red square, the symbol of Quebec's student movement.
That has carried political risks for Marois. It has also brought Liberal accusations that the opposition is tacitly supporting violence, given that student demonstrations occasionally end in vandalism and clashes with police.
But the result in Argenteuil is proof, the PQ said, that Charest's rhetoric isn't working.
"The premier's strategy has been unmasked," said Stephane Bedard, the PQ's house leader.
"The strategy of associating anyone who doesn't agree with him to violence didn't even work in his stronghold of Argenteuil, which has been Liberal for 40 years."
Student leaders described the Argenteuil outcome as a comeuppance for a party that has insisted on raising tuition, despite widespread protests.
It's unclear whether continued demonstrations into the summer might boost Charest's popularity ahead of an election — one expected as early as September.
But the movement's leaders, who have vowed to campaign against the government in the next election, weren't buying that line of thinking Tuesday.
"I'm anxious to hear from those who said the student strike would benefit the Liberals," Gabriel Nadeau-Dubois, a spokesperson for the student group CLASSE, said on Twitter.
But it is far from clear that the student conflict — now approaching its four month — was a deciding factor for byelection voters.
There are no universities or colleges in Argenteuil, which mixes a suburban and rural population. It's hosted only one so-called pots-and-pan protest, which are held nightly in various parts of Montreal.
"I'd be cautious about making a direct link to the student strikes," said Youri Rivest, a vice president at the polling firm CROP.
"The dissatisfaction towards the Liberals is bigger than the student strike. It was there before (the byelection), during it and will be there after it."
If dissatisfaction towards the Liberals led to their defeat, there was no sudden upsurge in support for the PQ — whose vote totals changed little from the 2008 general election.
It was the Liberals who lost votes.
Some went to other parties, while some Liberal voters are believed to have stayed home. As is common for byelections, voter turnout was low in Argenteuil and even more so in Lafontaine, where only 26 per cent of registered voters bothered showing up.
Several Liberal cabinet ministers acknowledged the party could be hurt if their voters continue to stay home.
"What's important for me is that the silent majority expresses itself in the next general election," Natural Resources Minister Clement Gignac said in Quebec City.
"For that to happen there needs to be higher participation levels."
In both ridings, the upstart Coalition for Quebec's Future (CAQ) finished a strong third — leading to speculation it might split votes with the Liberals among the pro-tuition hike, anti-sovereignty crowd.
There is, however, some disagreement about how the CAQ will affect the vote results. For instance, in Argenteuil, the party ran a well-known former Bloc Quebecois MP, somewhat undermining the argument that it was splitting the federalist vote.
"Obviously in an election as close as this the CAQ makes the difference," said Rivest. "But the bigger issue was the small turnout by Liberal voters."
Other analysts suggested that former Liberal supporters were indeed at the polling booth, and they ended up voting for the CAQ.
"While the PQ's win in Argenteuil is the major story from last night, their victory has more to do with what was happening with the Liberals and the CAQ than any PQ strength," Eric Grenier wrote on his blog Three Hundred Eight.com, which analyzes political statistics.
"The Parti Quebecois did well to hold on to their vote, but it was the split between the Liberals and the CAQ that defeated Jean Charest's party in Argenteuil."
With the loss in Argenteuil the Liberal majority in the provincial legislature narrows to 64 seats, compared to 60 held by the opposition.