On April 21, 2017, she announced that she was running to succeed
Rana Bokhari as the leader of the
Manitoba Liberal Party. Former Manitoba Liberal leader and longtime MLA
Jon Gerrard and entrepreneur and teacher
Dougald Lamont also contested the leadership. Lamoureux led on the first ballot at the
leadership election but lost to Lamont on the second ballot. She was reelected in the
2019 Manitoba general election, in which she shifted from Burrows to the neighbouring constituency of
Tyndall Park. Gerrard and Lamont were the only other two Liberals elected, winning their respective constituencies of
River Heights and
St. Boniface. In the
2023 Manitoba general election, Lamoureux was reelected, Gerrard and Lamont were defeated, and no other Liberal was elected, leaving Lamoureux the only Liberal member of the legislature. On October 17, 2023, she was appointed as the interim leader of the Manitoba Liberals and served until
Willard Reaves was acclaimed as the new leader on September 29, 2025. On October 20, 2025, she was appointed as the co-Deputy Leader of the party, serving with Jasbir Singh. ==Electoral record==