The three Liberals who won the byelections that secured a majority government for Prime Minister Mark Carney earlier this month took their seats in the House of Commons on Monday.

The government moved quickly to make use of its new majority powers by introducing a motion to limit debate on a change to the House rules that would enable the Liberals to take control of committees.

The Liberals are looking to change the structure of committees to ensure they have a majority of members. Committees study legislation and other government business and have the power to call witnesses and require the production of documents.

Government House leader Steven MacKinnon said the changes reflect the “long tradition” in Parliament that majority governments also hold a majority of seats on committees — though he acknowledged the situation is unusual.

“Let’s agree that it does not happen often that governments change status such that they grow to have a majority of the seats in the elected chamber during the typical mandate,” he said.

Opposition House leader Andrew Scheer decried the move as undemocratic.

“The very first vote that these new Liberal MPs will pronounce on will be a vote to shut down debate. So welcome to the Liberal Party of Canada, you can check your soul in at the door and just follow whatever the whip tells you to do,” Scheer said.

The Liberals have enough voting members to force the changes through, in spite of the opposition.

There are now 174 members on the government benches after five MPs — four from the Conservative benches and one from the NDP — defected over the last six months.

Doly Begum, Danielle Martin and Tatiana Auguste took their seats on Monday after they were formally sworn in as members of Parliament on Saturday.

Begum and Martin are newcomers who replaced outgoing cabinet ministers Bill Blair and Chrystia Freeland in Toronto-area seats.

Auguste won the seat in the Bloc Quebecois stronghold of Terrebonne in a rematch after the Supreme Court of Canada invalidated the results of last April’s election in the riding. The court found that Elections Canada had made an error in the printed return addresses on some mail-in ballots and ordered the vote redone.

Auguste increased her one-vote margin in 2025 to more than 700 votes this year.

Most members of the Liberal caucus came to the Commons chamber to welcome their newest colleagues with standing ovations and a few hugs.

No more than two dozen MPs filled the sparsely populated opposition benches, and none of the other party leaders were there.

The new additions came on the same day NDP MP Alexandre Boulerice announced that he was leaving the party to sit as an Independent MP before he resigns to run provincially for the Quebec Solidaire this fall.

The departure leaves the New Democrats with just five seats in Parliament. The party’s new leader, Avi Lewis, is not an MP.

“I’m not fazed by this,” Lewis said Monday, adding that Boulerice began considering the move to provincial politics well before he was chosen as the leader.

A byelection must be called within six months of Boulerice’s resignation in his riding of Rosemont-La Petite-Patrie.