TORONTO — The seemingly benign decision to stick a Liberal Party lawn sign in her front yard has brought a new ritual to Marla Waltman Daschko’s morning routine. Ms. Waltman Daschko walks around her Volkswagen Passat station wagon and peers underneath the chassis, searching for potentially deadly sabotage.

She is not alone, at least in parts of Toronto, when it comes to kneeling and peering at underbellies of cars usually seen only by mechanics. Last weekend, more than 30 Toronto residents awoke to find the brake lines on their cars severed, their telephone and cable television lines cut and political graffiti gouged into automobile paint and scrawled on their homes. The sole link among victims: a lawn sign promoting a Liberal candidate in the current federal election campaign.

The sabotage occurred in two leafy, upper-middle-class residential neighborhoods, where raccoons raiding garbage pails are normally a bigger concern than crime. The episodes have provoked bafflement, anger and defiance. They have also brought a tinge of nastiness to an election campaign short on drama.

Ms. Waltman Daschko briefly removed her lawn sign on Oct. 4 at the suggestion of the police after the first attacks, which occurred overnight on Oct. 3. But she put it back up before going to bed, she said, partly after considering the history of her Jewish ancestors.

“Perhaps because it’s the High Holidays but I thought of my parents and my grandparents and what they went through to assert their faith,” she said. “It’s shocking that in Canada, in Toronto and in the 21st century that this could happen when all we’re doing is supporting a very mainstream political party.”

The Toronto Police Service has established a task force to investigate the attacks and has strengthened patrols in the two affected neighborhoods. (By Wednesday night, Ms. Waltman Daschko had received two visits from officers making sure all was well.) But the police have offered no comment in public, or to victims, about who or what may be behind the attacks.

The crimes fit a distinctive pattern, victims say. The brake lines on the cars, some parked on streets, were cut using a knife. The scratches on the cars similarly seem to have been inflicted with a knife. The most distinctive element is the graffiti. It generally takes the form of either the party’s name or the name of a prominent Liberal politician (including the premier of Ontario who is not involved in the current federal vote) followed by the word “Lies” — all spray-painted in a tidy cursive script.

Around the corner from Ms. Waltman Daschko, Brent Johnston and Meredith Strong escaped the graffiti on their house, but not the car sabotage.

Near noon, Mr. Johnston jumped into their nine-month-old hatchback to pick up their children from a karate class. As he backed out of the driveway, dashboard warning lights flashed the word STOP, but the brake pedal was responding only sluggishly.

“It was very, very eerie,” Mr. Johnston said. Some residual strength in the brakes and the car’s slow speed allowed him to stop the vehicle, he said. Suspecting a mechanical fault, he switched to the family’s other car and asked his wife to call the dealer. It was only after the dealer told her she was the second customer to call with such a complaint that day that she looked at the passenger side of the car and found the two large Ls — presumably meaning “Liberals Lie” — gouged into the doors.

Other drivers had more terrifying experiences. Andrew Lane, who works for Carolyn Bennett, the Liberal candidate in the area, found that his brakes were nearly gone as he neared a major cross street. He managed to stop but not without narrowly avoiding a collision with a bus.

Ms. Bennett, a former minister of public health, found herself on Oct. 4 lending cellphones to supporters whose lines had been cut and driving them on errands after the reports of vandalism came into her campaign office.

During the 2006 election, Ms. Bennett won her Parliament seat by a wide margin. While she has a high profile, she does not have a reputation for highly partisan politics. Nor are any of her opponents particular firebrands.

Another series of attacks, which occurred on Oct. 4 and 5 were directed at supporters of Gerard Kennedy, who is running in another part of Toronto.

Like many people, Ms. Bennett, a physician, discounts the idea that another campaign is behind the attacks.

“In some ways, I don’t think this has anything to do with me,” she said in an interview. “It’s an unwell person or group of people who are doing this and not caring about the consequences. All of a sudden the family doctor in me bubbles up and I ask, What’s wrong with these people?”

The vandalism has continued. On Friday, Senator Jerry Grafstein, a prominent Liberal, found that the interior of his Cadillac had been pulled apart and damaged while it was outside his Toronto home. He has a lawn sign.

In Canada, campaign buttons are only worn by candidates or their staff, and political bumper stickers are rare. That leaves the lawn sign as the only medium for personal political expression. Ms. Bennett and her staff called the nearly 1,000 people with signs to ask if they wanted them removed. About 14 took up the offer, but more than 100 new people have since asked for signs as a challenge to the vandalism.

Mr. Johnston is among those who kept his Liberal sign despite the vandalism. (Ms. Strong, for the record, said she was nonpartisan.) Mr. Johnston said he still believed that how ever old-fashioned they seemed in the age of the Internet, lawn signs were an important part of democracy.

“If the signs weren’t up, how many people would even know there’s an election?” he said.

By IAN AUSTEN