Mitt Romney, a former Republican presidential nominee, will stump for Ohio Gov. John Kasich. (Gregory Bull/Associated Press)

Mitt Romney, the 2012 Republican presidential nominee, will make his debut on the 2016 campaign trail Monday by stumping with Ohio Gov. John Kasich in a last-ditch push to defeat Donald Trump in that state.

Kasich and Romney will campaign together in North Canton and Westerville on Monday, one day before Ohio's winner-take-all primary election.

News of Romney's planned appearance in Ohio was first reported by NBC News and confirmed by a Kasich campaign official.

Romney, a former governor of Massachusetts, is not endorsing a candidate, but has emerged as a leading Trump critic and has been complimentary of and helpful to all three Republicans trying to topple the front-runner: Kasich and Sens. Marco Rubio (Fla.) and Ted Cruz (Tex.).