Peter Van Loan, the government's House leader, appeared to set off the incident when he stormed across the floor of the Commons to confront his NDP counterpart, Nathan Cullen.
Microphones were shut off but video tape shows Van Loan waving his finger at Cullen and speaking in a heated manner.
NDP Leader Tom Mulcair, Cullen's seat mate, stands up, whereupon a number of New Democrats surround Van Loan and appear to urge him to leave.
Finally, Defence Minister Peter MacKay rushes over, puts his hand on Van Loan's shoulder and ushers him back across the centre aisle of the Commons to the government benches.
The contretemps was sparked by an NDP attempt to have a vote on the government's omnibus budget bill ruled invalid because Finance Minister Jim Flaherty had been absent, even though he was named as the mover of the motion to pass the bill.
Speaker Andrew Scheer dismissed the matter Wednesday as a technical foul-up, but an angry Van Loan apparently felt compelled to register his annoyance directly with Cullen.
In a statement issued Wednesday night, Van Loan said he walked over to the NDP benches to discuss the vote issue, a snafu he blamed on Deputy Speaker Joe Comartin, a NDP MP.
"I conveyed my disappointment to the NDP House Leader for the hypocrisy of his complaint which related to a mistake by a member of his own caucus last night," Van Loan said.
"It is normal for me to speak with the opposition House Leaders. I was however surprised how Mr. Mulcair snapped and lost his temper."
The New Democrats painted a slightly different picture.
According to the NDP, Van Loan stormed across the aisle, loomed over Cullen as he sat at his desk and began swearing at him and waving his finger in his face. Van Loan blamed Cullen for the procedural snafu and warned him to never do it again, the NDP said.
At that point, Mulcair stood up and warned Van Loan not to threaten his House leader.
Conservative MPs said Mulcair swore repeatedly at Van Loan. New Democrats conceded he might have done so but only after he was provoked by Van Loan.
For his part, Cullen wouldn't specify precisely what was said but indicated that Van Loan used "a lot of real bad language, threatening language."
"It was inappropriate and then Tom said, 'Don't threaten my House leader,' and that's when we all sort of stood up to make sure it didn't go any further," Cullen said in an interview.
"You've got to get him away because nothing good happens if he stays there talking that way."
Cullen said Mulcair's intervention was aimed at making Van Loan back off.
"For the Conservatives to try to spin his out that somehow (Van Loan) was the victim, I mean, give me a break ... That's ridiculous."
The NDP may lodge a formal complaint about Van Loan's conduct with Scheer, who stood by saying nothing during the incident.
"It's an option but I'm looking for options that are helpful," Cullen said, adding that his primary goal is to improve decorum in the Commons.
Meanwhile, Interim Liberal Leader Bob Rae offered a light-hearted take on Mulcair and Van Loan's exchange.
"If those two did have a fight, it would make Sumo wrestling look like a fitness contest," he joked at the Liberal Christmas party Wednesday night.
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