OTTAWA -- Stephen Harper likes to tweet about taxes. Canadians on Twitter, on the other hand, link the Conservative leader to another word: Duffy.

That is one of the findings from Twitter Canada on election chatter over the first four weeks of the campaign that gives hints about which leader is getting a message across on social media.

The prime minister's name continues to be associated more with the trial of Sen. Mike Duffy than with the economy, taxes or jobs, fuelling partisan attacks on Harper.

The tweets were most noticeable during the testimony of Harper's former chief of staff, Nigel Wright and when evidence suggested that Harper's current chief of staff, Ray Novak, knew about his predecessor's plan to cover Duffy's questionable housing claims.

As mentions of Duffy rose, so too did mentions of the word change in relation to NDP Leader Tom Mulcair and Liberal Leader Justin Trudeau.

"People are interested in change a lot more than they were at the beginning of the campaign," said Steve Ladurantaye, Twitter Canada's head of government partnerships.

The Duffy trial and Novak's denial he knew of Wright's payment plan, "seems to have some staying power," Ladurantaye said.

The prime minister has tweeted from his official account 26 times since he opened the 11-week federal campaign at the start of August. He has focused on taxes, jobs and the economy, in that order, Twitter Canada says.

His two main opponents have taken to Twitter more often so far -- Mulcair has tweeted 225 times, Trudeau 471 times -- and seem to tweet most often about the same theme: Change. Mulcair, however, tweets more about "experience" than the economy, while Trudeau tweets more about the economy followed by the "middle class."

"You see them driving the partisan agenda," Ladurantaye said.

Green Party Leader Elizabeth May is the most active party leader on Twitter, sending out 1,357 tweets through the first four weeks of the campaign, talking about the economy, "democracy," and veterans -- in that order.

Twitter Canada research has shown that May engages more often with other Twitter users than any of the other party leaders. That may explain why the top themes in her tweets don't match those of her opponents.

"She's out there engaging people on the stuff they're talking about," Ladurantaye said. "She's not confining herself to the talking points or the main issues."