HALIFAX — Prime Minister Stephen Harper held his news conference Thursday and declined to tell journalists — corralled behind a yellow fence over 12 metres away — why he limits the daily encounters to just five questions.

The episode highlighted the brewing issue of whether Harper, as the apparent front-runner in the race, is running a campaign in a bubble to prevent embarrassing mistakes.

After several days, it is clear his daily schedule is carefully designed to minimize political risk. Harper has not done any "walkabouts" on city streets where average voters can meet him. Moreover, the photo-ops with voters — such as at a seniors' home and a deli — have been pre-arranged. Also, people who attend rallies must be on a list to gain entry to the event.

Harper only provides one news conference per day, and it is specifically designed to ensure that it is not free-wheeling. Journalists who are travelling with his campaign tour are, as a group, only allowed to ask four questions. One more question goes to a local journalist at the news conference.

On Thursday, Harper was asked to explain why — when Liberal leader Michael Ignatieff and NDP leader Jack Layton provide news conferences with no limits on questions — he insists on no more five questions.

Harper chose not to answer that question and moved on to the next questioner.

When journalists then pressed him for an answer to the question he ignored, Harper said. "If there's another subject I'll answer it."

That led to another question from a journalist, who noted that politicians such as himself promise openness and accountability. With that in mind, he was asked again, why the limit on questions during the campaign?

"If there are other subjects I'm not addressing, I'll take them. What's the subject? One subject."

Journalists asked another question, about Canada's position about the conflict in Libya. Harper answered and then ended the news conference.