Nigel Wright, a key witness in Sen. Mike Duffy’s trial, took the stand Wednesday. Here are the highlights of his first day of testimony:

What “good to go” meant

Wright defended a statement he made in a Feb. 22, 2013 email, in which he told Duffy's lawyer and several PMO officials that "we are good to go from the PM."

He said “good to go” meant Prime Minister Stephen Harper agreed it was important that Duffy repay his Senate housing expenses, that regardless of any legal or technical entitlement “they also had to be right and appropriate.”

"'Good to go' means that the points I wanted to raise with the PM had been raised and that we could proceed with the plan," Wright testified.

Harper did not know how Duffy’s disputed expenses would be repaid

Wright testified that Harper did not know about the original plan to have the Conservative Party fund repay Duffy’s expenses when they were believed to be around $32,000.

Harper also did not know that Wright personally footed Duffy’s bill when it turned out to be $90,000, he told the court.

Duffy discussed the residence issue with Harper

Wright recalled a "business conversation" Duffy had with Harper at a caucus meeting on Feb. 13, 2013, during which he said the senator explained to the prime minister why he was claiming his P.E.I. residence as his primary home.

Wright told the court that he advised Harper that Duffy should be claiming his Kanata home near Ottawa as his primary residence. Harper agreed and told Duffy to pay back the money, Wright said.

PMO staff were heavily involved in negotiations with Duffy and his lawyer

Emails tabled in court show drawn-out and sometimes tense discussions between Wright, PMO lawyer Benjamin Perrin and other PMO staffers about Duffy’s expenses and how they would be repaid. In one email to Chris Woodcock, the PMO’s director of issues management at the time, Wright wrote: “For you only: I am personally covering Duffy’s $90K.”

Duffy demanded that he be acknowledged as a legitimate representative of P.E.I.

At one point during repayment discussions with PMO staff, Duffy’s lawyer came back with a list of conditions under which Duffy would accept a deal offered by Sen. David Tkachuk, according to the emails and Wright’s testimony. Among those conditions was that the government issue a "written acknowledgement that Senator Duffy meets and has always met all requirements necessary to sit as the Senator from PEI."

Wright now regrets covering Duffy’s expenses

Wright told the court he felt he had an “obligation” to help Duffy repay his expenses, after the original plan to have the Conservative Party cover them fell apart. But he said he “lived to regret it.”

“There were a whole lot of connotations associated with it that I didn't really think through,” he said. “If I had, I might not have done it."