05/20/2013 02:16 EDT | Updated 07/20/2013 05:12 EDT

WATCH: Nigel Wright Resignation: NDP Calls On RCMP To Investigate

OTTAWA - Conservatives gathered Monday night to mourn the passing of a key architect in their rise to power — and to brace for the toughest test Prime Minister Stephen Harper's government has faced since taking office on a promise to clean up politics in the national capital.

A who's-who of Tories had few words for the handful of assembled journalists at Ottawa's National Arts Centre, where a memorial service was being held for Conservative senator and party stalwart Doug Finley, who died earlier this month.

Solemn-looking cabinet ministers, senators, aides and strategists declined to speak to reporters about a burgeoning Senate scandal which is likely to receive continued attention this week.

Harper is expected to address the Conservative caucus Tuesday morning before departing to South America for trade talks.

The prime minister will no doubt field questions about his former chief of staff Nigel Wright, who quit his job this weekend over his role in the controversy over Senate expenses.

Wright gave embattled Sen. Mike Duffy a personal cheque for $90,000 to repay his housing claims — a gesture that likely never would have become public knowledge had the former broadcast journalist exercised a greater degree of discretion.

Last week, CTV News reported that Duffy told several people about the payment. On Sunday, Wright resigned.

"My actions were intended solely to secure the repayment of funds, which I considered to be in the public interest, and I accept sole responsibility," Wright said in a statement.

"I did not advise the prime minister of the means by which Sen. Duffy's expenses were repaid, either before or after the fact."

Wright's resignation followed the exit of two senators from the Conservative caucus. Duffy left on Thursday and Sen. Pamela Wallin — who is facing her own expenses audit — left on Friday.

Duffy did not respond to an email asking if he intended to be at the Senate on Tuesday.

The ethics commissioner is looking into Wright's repayment of Duffy's expenses. The federal New Democrats are calling on the Mounties to determine if Wright's payment to Duffy broke any laws.

The NDP's ethics critic, MP Charlie Angus, wrote to RCMP Commissioner Bob Paulson on Monday asking the force to look into the actions of Nigel Wright.

Angus said Harper has a duty to explain to Canadians just what happened.

"We haven't heard the prime minister say that a secret cash payment to a politician is wrong, and whether the prime minister knew, at what point he knew. He must have known something," Angus said.

"Because if it happened under his watch and he did nothing about it, that would be absolutely shocking."

At least one Tory MP was trying to put a decidedly optimistic face on a week that saw Harper lose two Conservative senators and his top aide.

Conservative MP Joan Crockett took to Twitter on Monday to trump her party's commitment to ethics.

"Our govt has the highest ethical standards demonstrated by 3 resignations: 2 from Senate caucus & the PM chief of staff," Crockett wrote.

"Those whose actions don't stand up to scrutiny, resign. Unlike the opposition. It's a clear demo of accountability folks from some other parties could emulate. #liberals"

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