Conservative Leader Stephen Harper returned to using Liberal Leader Justin Trudeau's full name during a campaign speech Tuesday, but was still forced to field more questions about why he’s repeatedly referred to his opponent by just his first name.

On Monday, the first full day of the election campaign, Harper referred to Trudeau several times as "Justin" while addressing a rally of supporters in Kingston, Ont.

But on Tuesday, while promising a new home renovation tax credit during a campaign stop in Toronto, Harper returned to using the full names of both his main opponents.

CTV's Laurie Graham asked Harper about his choice of words and whether he was concerned that Canadians might find it disrespectful or belittling for one party leader to refer to another by his first name. Harper replied he uses many names for the Liberal leader.

"I use that sometimes and sometimes I don't," Harper said. "That's how, in our experience, Canadians generally refer to him, because that is how the Liberal party itself has branded him."

For his part, Trudeau is brushing off the moniker choice. When CTV's Omar Sachedina asked him about Harper's choice of names, Trudeau chose to ignore the question. When asked about it again by another reporter, Trudeau responded, "Clearly, it's a distraction." He then went on to say he is "staying focused on Canadians."

Ahead of Harper's address Tuesday, Conservative campaign spokesman Kory Teneycke tried to fend off further questions on the moniker matter by addressing reporters privately. He said Trudeau himself has been running his campaign from a website simply titled Justin.ca and has been using banners with just his first name as well.

"I think the Liberal Party invested a lot of money into branding him as Justin and not surprisingly, that's how most Canadians know him," he said.

He said Harper has used many names for Trudeau from "Leader of the third party" to "Mr. Trudeau," but for their advertising, they are referring to Trudeau "as he is known, and he is known as 'Justin'," Teneycke said.

Anna Esselment, a political science professor at the University of Waterloo, says there is likely more of a deliberate strategy in Harper's name choice.

"When you refer to somebody just by their first name, it feeds into the Conservative strategy of defining Justin Trudeau as young and inexperienced," she told CTV News Channel Tuesday morning.

She said Harper would likely never begin referring to NDP Leader Thomas Mulcair as "Tom," but he does appear willing to use a less formal first name for an opponent as young as Trudeau.

As well, Esselment says Harper may be trying to avoid using the "Trudeau" name because many Canadians – especially those in their '60s and '70s – still have an emotional attachment to the name made famous by the Liberal leader’s father, former prime minister Pierre Trudeau.

"I imagine that Stephen Harper wants to cut that off," Esselment said. "So by not saying 'Trudeau,' he doesn't make that connection that many voters make to Trudeau's dad."