OTTAWA - Beware the Klingons. Or is that cling-ons?

Security preparations for maybe the most popular American president ever to visit the Canadian capital are contemplating a new and challenging menace: the sycophant. They're known as Klingons in the wry parlance of Ottawa logistics planners.

But as security headaches go, glad-handing parliamentarians, star-struck political staff and crowds of public well-wishers are a welcome tradeoff from the usual angry throngs of sloganeering protesters that have often dogged U.S. presidents.

Officials preparing for Thursday morning's arrival of President Barack Obama insist the security issues are similar whether it's a Dubya or an Obama.

"I understand, obviously, with this particular president . . . many people will want to just come see him and get a glimpse of him," said Supt. Mike McDonald, the RCMP security event co-ordinator.

"But with respect to our (security) measures, they will remain the same."

In other words, it's way over the top.

An armour-plated, hermetically sealed, blast-proof presidential limo nicknamed "the Beast" has been flown in from Washington.

Air space over the capital will be restricted all day Thursday.

Multiple city streets will be blocked starting at 7:30 am for Obama's arrival three hours later.

And Parliament Hill, Canada's seat of government, has been turned into a de facto foreign satellite of the American security apparatus.

"I'm about to wonder, is it an Obama visit, honestly, or is it a United States security service visit in Canada?" Senator Marcel Prud'Homme sniffed Tuesday from his office in Parliament's Centre Block, where security sweeps were already well underway.

"We have to protect our guest, but we must not lose our marbles, either."

Catching even a glimpse of Obama in the flesh will be unlikely for the public expected near Parliament Hill.

Busloads of fans are making the hours-long drive from southern Ontario, but even if they manage to pass security checkpoints and get a coveted perch behind the temporary barricades on the snowy grounds below the Peace Tower, the RCMP's McDonald said they'll likely see nothing more than the motorcade.

Security consultant Chris Mathers, a former RCMP officer, said a friendly crowd helps police only up to a point. He likens Obama fans to the screaming mobs that once chased the Beatles.

"They didn't want to hurt the Beatles, they just wanted to see them, but it still scared the hell out of the Beatles."

However, identifying those aggressors "with a different agenda," said Mathers, is much harder when you're facing an angry mob garbed for tear-gassing.

"If you've got a crowd of relatively happy people, you'll be able to pick out the nuts a little bit easier," he said.

"If it was George Bush, every nutjob and fringey so-called activist in the world is going to be out there trying to get his face on TV."

Unlike Bush's visit in 2004, Ottawa police have not recommended that businesses near Parliament Hill board up their windows.

Oddly enough, a considerable amount of concern appears to revolve around what happens once Obama is inside the secure Parliament Buildings.

Even though the Commons and Senate are not sitting this week, some officials are concerned about parliamentarians overcrowding a large room where Obama and Prime Minister Stephen Harper will hold a brief joint news conference. It's that Klingon effect.

Parliament Hill staff are being encouraged, if not ordered, to stay in their offices but there can be no such limitations for MPs and senators.

Prud'homme, a former Liberal MP appointed to the Senate by Conservative prime minister Brian Mulroney who sits as an Independent, said he's undecided whether he'll attend the news conference.

"I know I will have freedom of circulation - senators and members of the House (do)," said Prud'homme. "I usually attend every major event on the Hill. It's my House, you know."

But New Democrat MP Paul Dewar, who represents an Ottawa riding, said most MPs will be at home in their ridings attending to constituency work.

An Obama booster, Dewar is shrugging off the visit.

"There's no real access," he said. "You'll be amongst the crowds watching the limo drive by and catching a glimpse - maybe - in the hallways of Parliament Hill."

"I don't think you're going to get a handshake."