"In a voice loud enough for several of their cabinet colleagues to hear, Flaherty told Kenney to "shut the f--k up" about Ford.
Kenney responded angrily in kind, and although the two men were separated by four other ministers, alarmed caucus colleagues, who requested anonymity, were concerned the bilious debate might escalate beyond their control.
"I thought they might come to blows," said one MP who was not authorized to speak publicly about the incident.
Another MP said there was shock at the sight of two senior ministers battling in such a public way....
Kenney did not deny the confrontation took place.
"Not everyone agrees with each other on everything all the time," Kenney said. "There is always going to be some disagreements from time to time."
Kenney and Flaherty are Harper's most trusted ministers and control the key economic and job creation portfolios, so it seems lots of tension in the Conservative caucus these days.