The RCMP confirmed this week it will not pursue charges against Nigel Wright, the prime minister's former chief of staff, over a $90,000 payment he made to cover Senator Mike Duffy's ineligible expenses.

But the federal Ethics Commissioner is still looking into the matter and the RCMP continues its investigation of Duffy.

What does the RCMP's decision mean for Wright, for Duffy and for Prime Minister Stephen Harper? Is the Senate scandal nearly over, or will it be re-ignited?

This week on CBC Radio's The House, host Evan Solomon looks at the impact of the RCMP's decision to clear Wright.

Charlie Angus, the NDP's ethics critic, believes the RCMP has an obligation to explain its decision.

"Otherwise, it leaves a really clear impression for Canadians that something is fundamentally wrong when the man (who) is as close to the prime minister as you can get walks away from charges when there's such a paper trail, and such a series of allegations, that were laid out by the RCMP."

"So we have to ask, what's going on in Ottawa in 2014 when these kind of secret payouts are made, can be made with the collusion of a whole series of top senators, the Conservative Party, the prime minister's lawyer — and then when push comes to shove, the RCMP say 'no charges,'" Angus said.

"Those are valid questions Canadians need to hear answers to."

Paul Calandra, the parliamentary secretary to the prime minister, points to the detailed court documents filed by the RCMP as proof the Mounties conducted a thorough investigation.

"The reality is the ITO outlined just how serious the RCMP took this investigation. They did it for over a year they've been investigating, they're still currently investigating Senator Duffy and Senator (Pamela) Wallin.

"I have confidence that the RCMP is a very professional force and they're able to make decisions, that they felt no pressure one way or another. I have complete confidence in them to do their job," Calandra said.

You can hear the full exchange this week on The House.

Also this week, Conservative senators are now among the growing list of people calling for changes to the Fair Elections Act. Senator Linda Frum, a member of the Senate's legal and constitutional affairs committee, is on the program to outline how she feels the bill should be amended and Democratic Reform Minister Pierre Poilievre explains whether he's open to such changes.

Yuriy Sergeyev, Ukraine's ambassador to the United Nations, and Ukrainian Ambassador to Canada Vadym Prystaiko discuss the potentially explosive situation in their country and what comes next.

And finally, In House panellists Chris Hall and Tasha Kheiriddin explore the remaining questions in the Senate-PMO scandal.