Adrian Wyld/The Canadian Press Green Party Leader Elizabeth May speaks with the media in the Foyer of the House of Commons on Parliament Hill in Ottawa on Oct. 23, 2018.

OTTAWA — Federal parties took turns Tuesday knocking each other for insufficient action on climate change, but it was Elizabeth May who threw the sharpest barb at Andrew Scheer. Following an announcement that the government will be delivering tax rebates in four provinces that rejected the federal plan, the Green Party leader called the Conservative party's antagonistic position strange in light of carbon pricing's history. "They seem to also want to ignore that carbon pricing, as a mechanism, was invented in the United States by Republicans who wanted to find a market mechanism so they could avoid heavy regulation," May said. The rebates will help the Liberals court votes, May said, and will "leave Andrew Scheer and his cowardly negligence exactly where it belongs: in the spotlight of uselessness."