With Prime Minister Stephen Harper skipping the Monday session, as is his practice, it fell to Heritage Minister James Moore to deflect a barrage of Senate questions.
But recent missteps for both NDP Leader Tom Mulcair and Liberal Leader Justin Trudeau made it easy for the government benches to blunt their attacks.
Mulcair wanted to know when Harper would provide answers about the scandal — specifically the $90,000 cheque written by the prime minister's former chief of staff to cover Sen. Mike Duffy's questionable expense claims.
"When will the prime minister takes responsibility, show accountability and finally start answering questions?" Mulcair thundered.
Moore countered by bringing up NDP MP Tyrone Benskin, who Mulcair fired from his critic's job last week after he admitted he owed almost $60,000 in back taxes.
How many more of Mulcair's MPs are behind in their taxes? Moore wondered aloud.
"If he really believes in accountability, maybe he would tell this House how many more NDP MPs are not paying their taxes."
Trudeau got up to promote Liberal efforts to move a motion before the Senate ethics committee to study the Senate scandal and call both Harper and Nigel Wright, his former chief of staff, to testify.
Instead, he got a pointed reminder of his comments about Senate reform, published Friday in Montreal's Le Soleil, that landed him in hot water. Trudeau was expressing his opposition to abolishing the Senate when he pointed out that it gives Quebec an advantage — more seats than Alberta and British Columbia.
"It is kind of interesting to see him stand in the House and pretend as though he actually cares about Senate reform because he does not," Moore said.
"All Canadians should be served by national institutions and the Liberal leader should stop dividing Canadians again and again over these matters."
Outside the House, Trudeau stood by his remarks as "a statement of fact, not of opinion."
"My comments were ... reflecting the numerical reality of the Senate and the challenges around reforming it," he said.
"We have a morass to get into to make any changes to the Senate, and both other political parties in the House are using discussions about the Senate to distract from what should be the most important issue of the day, which is their ethical shortcomings."