A New Democratic Party candidate was under fire Thursday for comments made online about war deserters.

The Liberals ramped up the pressure for the NDP to fire Andrew McKeever, who is running in the riding of Durham, east of Toronto.

McKeever posted comments on Facebook about war deserters, saying "American traitors" have no place in Canada. He also used obscenities in reference to women and threatened to beat up a critic.

Late Thursday, McKeever issued an apology for his comments, admitting they were "less than respectful."

"I took part in several online discussions over the last few months and was often a less than respectful contributor, exchanging insults with other members," McKeever said in his statement.

"I am deeply sorry for having offended anyone."

Conservative MP and International Co-operation Minister Bev Oda holds the riding after easily winning a second term in  2006, with the Liberals finishing second, ahead of the NDP.  Liberals won the riding in the three previous elections.

Earlier in the day, the tide was turned with several NDP candidates holding a news conference in Calgary to call for the resignation of a Conservative incumbent over comments linking crime with immigrants. Liberals also joined in the calls for the candidate to quit or be turfed by the party.

Asked about recent city shootings, Calgary Centre Conservative Lee Richardson told a local weekly paper that Canada has been too soft on crime.

"Particularly in big cities, we’ve got people that have grown up in a different culture," he said. "And they don’t have the same background in terms of the stable communities we had 20, 30 years ago in our cities … and don’t have the same respect for authority or people’s person or property."

Richardson later said he regretted the comments.

With files from the Canadian Press