OTTAWA - The Liberal and Conservative campaign machines will be missing some of their big wheels and quite a few cogs this time around.

Many lobbyists who've done everything from debate preparation to media relations in past campaigns, are taking a pass in 2011, frustrated by a lack of clear guidance from the lobbying commissioner on what they can or cannot do.

Added to the mix is a fear in Liberal circles that the Conservatives will slag them publicly for employing lobbyists, even though a few Tories who circulate in the lobbying world have popped up on Stephen Harper's team.

Sources say that includes longtime Harper adviser Ken Boessenkool, whose last entry in the lobbyist registry expired last September. Former Conservative Research Group director Jason Lietaer, now with lobbying and PR firm Enterprise Canada, will head up the campaign's communications arm. He was last registered to lobby in 2008.

But most other senior Conservative lobbyists, including veteran campaign hand Michael Coates, will be noticeably absent.

"We are hoping that when the Lobbying Act is reviewed later this year, the act will be amended to put lobbyists on the same footing as public servants when it comes to participating in elections ... After all, it is our democratic right to do so," Coates, president of Hill and Knowlton Canada, wrote in an email.

Television and radio political panels are about the only place most lobbyists with political allegiances are daring to tread over the course of the five-week race.

The reluctance stems from Lobbying Commissioner Karen Shepherd's interpretation of the rules regarding lobbyists' political activities.

Last year, she tried to clarify the murky area by saying that engaging in activities such as donating to a party, putting up lawn signs or going to a fundraiser is only advancing the private interests of a public office holder to a "low degree" and would be okay.

Sitting on the board of directors of an MP's riding association or organizing a fundraiser for them would likely put a lobbyist in a potential conflict of interest, in violation of the rules, she said.

But what of working on a party's national campaign?

Shepherd isn't as definitive on that point, saying lobbyists must carefully weigh the kind of work they're doing politically and what kind of lobbying work they think they'll do in the future. Temporarily deregistering as a lobbyist might not be enough.

Many have asked -- to no avail -- for Shepherd to provide some guidance in advance on whether specific political activities would put them in contravention of the rules.

Elizabeth Roscoe, a Tory who works at Hill and Knowlton and sits on the board of the Government Relations Institute of Canada, says lobbyists are faced with making an uninformed decision that they could later be punished for.

"You are penalizing individuals for their designation, without being proactive and identifying what they can do," said Roscoe. "Her guidance about putting up a lawn sign, being able to make a political donation, that really has not provided any specific guidance that people can really model themselves after."

But in an interview, Shepherd said the facts around a lobbyist's work and political activities could very well shift after she's offered them her opinion. She said it wouldn't be prudent to rule in advance, given that all her decisions are subject to judicial review.

"I feel that in fairness to them it would put them at risk should I provide a ruling, but it would also put at risk my ability to look into the matter in the future should there be allegations against this person, and I feel quite strongly that my neutrality and my ability to be fair would be compromised," Shepherd said.

The Liberal party sought a legal opinion to try to clarify the situation. According to insiders, it concluded there likely was no problem with lobbyists being involved on national campaigns. However, it allowed there was some ambiguity on the subject.

That ambiguity -- combined with fear of "the poisonous wrath with which the Conservatives might target certain people and ruin their careers" -- was enough to scare off lobbyists who'd been approached to work on the Liberal campaign, according to one insider.

Earnscliffe lobbyist Mike Robinson has been involved in every Liberal campaign since 1972. For at least two decades, he's represented the party in negotiations with television networks over the format for leaders' debates.

But Robinson will be sitting out this campaign.

"An awful lot of people like myself are saying, 'You know, until the rules are clear, just take a pass,"' he said.

"It's one of those situations where, without some clarity, people are just very nervous about putting their professional reputations at risk."

Robinson predicted the situation will be clarified only after someone launches a court challenge, which he predicted the rules would not survive.

"There's some basic freedoms of expression here and the right to get involved in the political process is pretty basic, in my view ... I think it's a fundamental breach of the Charter of Rights, I really do."

Those complaints don't get much sympathy from New Democrat MP Pat Martin, who says the rules should prohibit direct support from lobbyists.

"Active support in an election campaign is considered a donation in kind," he said. "A lobbyist can curry favour with a politician by emptying his office into a minister's election campaign."