The incident in Louiseville was similar to vandalism at two other Liberal offices earlier this week in Montreal and Gatineau. Union members also held a rowdy protest at a Montreal children's hospital this week.
No charges were laid, but the protests are a prelude to major demonstrations next week across Quebec that are expected to shut down a number of provincial services.
Michel Dupont, a regional head of the Quebec Federation of Labour, said the tactics are necessary to send a message to Premier Jean Charest.
"If we do nothing, the government will do nothing to change its policies," Dupont told RDI, Radio-Canada's all-news channel. "It's one of the few tactics at our disposal."
Upset health-sector unions held a news conference Friday to denounce a series of moves by Charest's government.
The Liberals have introduced legislation to merge some health-care operations and bargaining units, a move unions say will wreak havoc on seniority lists and force workers to abandon small, specialized unions.
Read More:
Unions target riding offices in protests, hint at new tactics next week
Note: Unions target riding of...

I think that says it all. He will destroy healthcare, cut taxes, and generally not get elected next time.
He\'s also leading the charge to scrape more money out of Ottawa\'s hands, and I think Paul Martin will give in to him and his provincial partners in crime.
The right-wing is destroying every province in Canada. So, what else is new ??
Social programs ? Going, going, soon-to-be-gone.
---
"Arrogance in Politics is unacceptable"
Jim Callaghan
Minden, Ontario
705-286-1860
www.misterc.ca
---
Dave Ruston
---
"Arrogance in Politics is unacceptable"
Jim Callaghan
Minden, Ontario
705-286-1860
www.misterc.ca
---
Dave Ruston
Wait!!! I\'m not a Troll anymore!!!
There were dozens of protests during the Mike Harris years, and it accomplished little or nothing. Why didn\'t we get violent more often?! Violence IS the answer. The public currently pays 200 000 for 3 bodyguards and a driver for Mr. Harris, as he receives death threats daily. (still)...apparently. Harris got egged in his first few months in office.....why did we stop? Let\'s tar and feather them, then burn them at the stake....we can finish it off by feeding them to skunks.
Wuddaya think?