overnment House Leader Peter Van Loan has apologized for using off-colour language during a verbal dust-up on the floor of the House of Commons with NDP Leader Tom Mulcair Van Loan acknowledged Thursday he used an inappropriate word during the confrontation.However, New Democrats weren't satisfied, questioning how Van Loan can remain government House leader after displaying so little regard for proper conduct.The incident erupted Wednesday after the NDP unsuccessfully attempted to invalidate a vote on the government's omnibus budget bill due to a procedural snafu.Microphones were shut off during the incident, but video tape shows Van Loan stormed across the centre aisle of the Commons, waving his finger at his NDP counterpart, Nathan Cullen, and speaking in a heated manner.Mulcair, Cullen's seat mate, stood up, whereupon a number of New Democrats surrounded Van Loan and appeared to urge him to leave.Finally, Defence Minister Peter MacKay rushed over and ushered Van Loan back across the aisle to the government benches.New Democrats say Van Loan provoked the contretemps, repeatedly dropping the "F-bomb" as he wagged his finger in Cullen's face. They say Mulcair came to Cullen's defence, warning Van Loan to stop threatening his House leader.