OTTAWA -- A cabinet minister invited Mike Duffy to speak to supporters in his B.C. constituency, but the local Conservative association only picked up part of the bill, a court heard Wednesday.

The suspended senator's trial drew its first witness from Parliament Hill, entering the realm of Conservative caucus meetings and party fundraisers.

Government whip John Duncan was called by the Crown to tell how he invited the now-suspended senator to speak at a riding event in June 2009. At the time, Duncan was aboriginal affairs minister.

Justice Charles Vaillancourt heard that Duffy had quickly developed a reputation in the caucus as someone who could help raise funds and stimulate interest in local riding associations.

"The message was that he came, that he spoke well and that people really enjoyed his conversation, his jokes and his talk," Duncan said of the former broadcaster.

Duffy has pleaded not guilty to 31 counts of fraud, breach of trust and bribery, including 18 related to trips he took at public expense.

Duncan said at least 120 people attended the dinner in Courtenay, B.C.

"A lot of my constituents and party members were quite interested because they watched Mr. Duffy on his show ... so there was a pretty high level of interest in meeting with him."

The local riding association paid for Duffy to stay two nights at a local hotel and for a few of his meals.

"Our (riding) president offered to pay the flight from Vancouver to Comox," Duncan said. "We actually received an invoice from Sen. Duffy's office and our treasurer refused to pay it, so we never paid it."

Duffy's travel expense claim indicates he billed the Senate $2,173 for the flight from Ottawa to Comox, B.C., plus a few meals and a car rental. A flight back to Vancouver to Comox was paid for by an unidentified event host -- possibly the Fraser Institute, where he spoke a few days later.

Duffy's daily calendar entries, which are court exhibits, say he also met veterans' representatives in Comox on pension issues and with local mayors. Duncan says he was unaware of those meetings and was surprised that he didn't know about them.

The Crown has been trying to demonstrate that Duffy billed for travel that was for clearly personal or political purposes.

The defence, meanwhile, has taken pains to demonstrate that in the years covered by the charges, the Senate rules said partisan activities were an inherent part of a senator's parliamentary functions.

"So if I understand correctly, he came to this event in your riding across the continent at your request," said defence lawyer Donald Bayne.

"Right," said Duncan.

An analysis of Duffy's calendars between late 2008 and 2012 indicate he engaged in political activities with at least 74 current and former MPs.

Another trip Duffy took on Senate business, in 2010, also came up at trial Wednesday and the core allegation around it seemed shaky.

Crown attorney Mark Holmes said in his opening statement last month that Duffy and his wife travelled at public expense in July 2010 to meet then-MP Dean Del Mastro and attend a dog show in Peterborough, Ont.

"They arrange to acquire a puppy and drive home. That is portrayed as public business," Holmes said on April 7.

"It's in effect a shopping trip."

But two of the Crown witnesses who testified about the Peterborough travel did not directly corroborate the "shopping trip" part of the allegation.

Former dog breeder Barbara Thompson testified by telephone from New Brunswick that she wasn't at the dog show in Ontario. The Duffys purchased a dog they had seen at her home earlier.

The court also heard from broadcaster and columnist Ezra Levant, who said he wrote two or three non-partisan speeches for Duffy in 2010 and 2011.

Some of the 31 charges are linked to $65,000 in contracts Duffy arranged with companies owned by an Ottawa friend, Gerald Donohue. Those companies, in turn, sent payments for services to other individuals, including Levant.