The seat became vacant when Brown died of a sudden heart attack in his Parliament Hill office in Ottawa.

[3] In addition, Edwardsburgh/Cardinal town councillor and federal riding association president Michael Barrett,[4] government-relations specialist Stephanie Mitton,[4] and Anne Johnston,[5] a former aide to Leeds—Grenville—Thousand Islands and Rideau Lakes MPP Steve Clark also ran for the Conservative nomination.

Former Canadian Senator and interim Leader of the Opposition in the Ontario Legislature Bob Runciman was rumoured to be interested in seeking the Conservative nomination[6] for the by-election but decided against it after his wife encountered some health issues.

[7] Barrett won the nomination at a local party convention at the Brockville Memorial Centre on August 11 in a contest that ran to a fourth ballot.

[11] The Speaker's warrant regarding the vacancy was received on May 3, 2018; under the Parliament of Canada Act the writ for a by-election had to be dropped no later than October 30, 2018, 180 days after the Chief Electoral Officer was officially notified of the vacancy via a warrant issued by the Speaker.