Campaign office windows smashed. Lawn signs set ablaze.

The longer the campaign and the tighter the race, the nastier the ground war gets.

While the party leaders battle it out on the national stage, a different fight is playing out at the local level, with many candidates across the country targeted by vandalism, pranks and, in at one least one case, arson.

In that serious incident, a Stephen Harper supporter in Harper's home riding of Calgary Heritage had a sign posted on his back fence set on fire, causing damage to his shed and threatening his home.

A lawn sign in Stephen Harper's home riding of Calgary Heritage was set ablaze, destroying a supporter's garage. (Provided to CBC)

Fortunately, a taxi driver driving by witnessed the flames and alerted the homeowner.

Police in Kingston, Ont., were called to investigate a string of attacks on the campaign offices of the three major parties earlier this month. Windows at three locations were smashed with rocks or hammers.

The fire could have spread to the home if a taxi driver hadn't stopped to alert the homeowner. (Provided to CBC)

And in a more bizarre act of sign vandalism, a young man was captured on video taking a run at — and knocking down — an NDP candidate's signs in a Mississauga, Ont.

Canada's election watchdog has received hundreds of complaints about dirty tricks and rule-breaking on the hustings, and the office is expecting that number to crest in the homestretch of the campaign.

So far, 320 official complaints have been lodged with the Commissioner of Canada Elections, an independent body that enforces rules around elections and referendums. The office cannot divulge specific details about complaints or confirm what investigations are under way, but misleading robocalls, lawn sign vandalism and bending the rules around advertising and expenses are all potential causes for complaints, according to its website.

Jean-Pierre Kingsley, Canada's former chief electoral officer, said it is usually tough to track the source of wrongdoing, especially in cases of the defacement or destruction of signs.

This Mississauga dude is pretty hard-headed about his dislike of the NDP. <a href="http://t.co/0Xr40qCB2u">pic.twitter.com/0Xr40qCB2u</a> —@kick1972

Vandals or political operatives?

"It's very hard to tell. It could be vandals, or it could be political operatives from the opposing camps," he said.

But whether it's destruction of campaign material, misleading information or crank phone calls, those "dirty tricks" can often backfire, garnering sympathy for the target, Kingsley said.

.<a href="https://twitter.com/neufast">@neufast</a> while out taking pics have you seen who did this to my signs? What do they say about stones & glass houses? <a href="http://t.co/3R3yhneDXg">pic.twitter.com/3R3yhneDXg</a> —@PaulCalandra

In the final weeks of campaigning leading up to Oct. 19, Kingsley expects a bombardment of advertising.

With an extended writ period, political parties have had to stretch their budgets and save money for what will be a major blitz in the fight to the finish, he said.

And while the war of words won't likely be delicate, Kingsley said it's tough to nail a person or party for false or misleading ads.

"The courts have been very lenient in interpreting what is fair comment in elections," he said. "It's not like the Copyright Act, or the Truth in Advertising Act guidelines."

After the infamous "robocalls" scandal of the last election, NDP senior campaign adviser Brad Lavigne says his team will be "extremely attentive" to misleading calls and other voter-suppression tactics as the campaign counts down.

'Vigilant' about robocalls

"We're ever vigilant, and stemming from the Michael Sona case, obviously, as we get to the advanced voting day and Oct. 19 we are going to be proactively ensuring our supporters understand Elections Canada rules," he said.

Sona was the only person charged in connection with a misleading robocall that reached 6,000 voters in Guelph, Ont., in an attempt to keep them from casting ballots in the May 2, 2011, federal election. He was found guilty of one charge under the Elections Act. Between 150 to 200 people who received the robocall went to the wrong place to vote.

Michelle Laliberté, spokeswoman for the Commissioner of Canada Elections, said the office is anticipating a modest rise in the total number of complaints because of the longer election period but expects "the bulk" will come at the end of the election period and the weeks immediately following election day.