Partisan supporters of Prime Minister Stephen Harper -- led by Conservative staffers -- purposely drowned out media questions Saturday about a controversial endorsement from a man with links to the Air India bombing.

Harper was in Mississauga, Ont., where he hoped to use the venue of a Coptic Christian place of worship on Easter Weekend to promote his platform promise of a new office of religious freedom.

But two controversies about extremism overshadowed that message.

A Tory candidate in the Toronto suburb of Scarborough has been shown to be a vocal supporter of the banned Tamil Tigers, prompting Conservative cabinet minister Peter Kent to say someone in his party's organization "obviously dropped the ball."

And a Vancouver candidate is trying to distance herself from an endorsement from a high-profile Sikh advocate who has long been linked to the Air India bombing and the controversial Babbar Khalsa movement.

The prime minister shrugged off both controversies.

Harper said Tamil candidate Ragavan (Gavan) Paranchothy -- whose recent on-air credits include calling the Tigers "heroes" and "freedom fighters" -- has renounced the violent Sri Lankan separatist movement.

"Our candidate in Scarborough has been very clear on his rejection of the Tamil Tigers, very clear on that," said Harper.

Paranchothy did issue a statement to that effect. But it hasn't stopped Peter Kent, Harper's environment minister, from disassociating himself from his fellow Toronto-area candidate, withdrawing a written endorsement and stating there was a "lack of due diligence" in permitting Paranchothy to run under the Tory banner.

Harper did not address his environment minister's concerns about Paranchothy.

But it was on the subject of Ripudaman Singh Malik and his public endorsement of Conservative candidate Wai Young that things got heated with Harper's supporters.

Young attended a meeting at a Sikh school in Vancouver that has charitable status and receives public funding, where Malik endorsed her run for office.

Malik was acquitted on charges related to the 1985 Air India bombings, which killed 331 people. But he's an acknowledged founder of the Babbar Khalsa movement and financial patron of other accused Air India conspirators.

Malik is also being pursued by the B.C. government for allegedly fraudulently claiming $5.2 million in legal aid for his Air India defence.

Harper said Young "was invited to attend a school. She attended in good faith."

"She has been very clear: she and her campaign have no links and do not welcome in any way Mr. Malik into this party. We are absolutely clear about that."

A reporter attempted to ask Harper if he actually believed Young could not know who Malik was when she received his endorsement.

A Conservative staffer near the reporter prompted the crowd of about 500 into sustained, aggressive applause that lasted more than a minute, drowning out the reporter's repeated efforts to get a response from Harper.

The crowd eventually surged to its feet to shield the prime minister from the line of inquiry, while staffers led cheers of "Harper!"

The front-running Conservatives are openly seeking a majority mandate for the first time in three general elections, and Harper is employing an extremely cautious campaign that has his opponents deriding the prime minister as "bubble boy."

Harper is providing only short, clipped responses to the few media questions his handlers allow. Journalists travelling with him at a cost of $11,000 per week are granted four questions per day.

Unlike the other party leaders, Harper holds all his media availabilities in rooms filled with partisan supporters -- a built-in cheering section for his press conferences.

He's not doing any mainstreeting and holds campaign events only in rooms with carefully screened supporters.

Harper's evasive, curt responses to questions about his candidates and extremism were especailly ironic given his introduction by cabinet minister Jason Kenney.

"We as Canadians have a special vocation, a special responsibility, to speak truth to power. To be a voice for the voiceless," Kenney told the crowd.

"To give real expression to our real values as a land of protection and freedom, particularly as we see a wave of persecution against people of faith around the world."

The citizenship and immigration minister said Harper has spoken out "in every instance, even when it wasn't obvious or convenient."

But Harper wasn't saying much Saturday.

In fact, Harper batted away another controversy Saturday, amid growing evidence a Conservative organizer -- and now senator -- Leo Housakos was the go-between as Montreal construction bosses attempted to influence who would be nominated president of the Montreal Port Authority.

Housakos is a close friend of Harper's communications director, Dimitri Soudas, who was described by the businessmen in a leaked phone conversation as the "big boss" in Quebec.

Harper was asked if Housakos will continue working for his campaign team, given the allegations of improper lobbying efforts and influence peddling.

"I think I've answered these questions. We're not making any changes here," Harper responded.

While the revelations about improper federal arm-twisting in the selection process for the port authority presidency have only just come to light in the past week, Harper called it old news.

He characterized the Montreal Port Authority nomination issue as having taken place "four years ago. I have nothing to add to that."

The Conservative campaign held one event in Mississauga, Ont., before flying six hours west to Vancouver Island, where Harper planned an afternoon rally in Campbell River, the riding of Conservative incumbent John Duncan.

Duncan is in a fierce fight with the NDP for the seat, which he won from the New Democrats by about four per cent of the vote in 2008 and lost by less than that in 2006.