Ohio Republican Gov. John Kasich's chief political strategist has a message for President Donald Trump: "Be careful what you wish for."

Earlier, a Fox News interviewer asked the president about the possibility of Kasich or retiring Sen. Jeff Flake, R-Ariz., running against him in 2020, and Trump responded, "I hope so."

John Weaver, the Kasich strategist, responded to the remark with a warning.

"Be careful what you wish for," Weaver said in a message to CNBC.

Kasich ran in the 2016 Republican presidential primary, which Trump won.