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.
When asked whether Kasich is leaning toward running as an independent or a Republican, Weaver responded "Open minded, though he is a Republican." Kasich has said publicly he's considering running either as an independent or a Republican for the White House.
Kasich's allies have previously told CNBC that an independent run may make sense due to Trump's growing popularity within the Republican Party. The Ohio governor's super PAC has been quietly raking in cash from megadonors across the country.
Kasich has been a vocal opponent of Trump's policies, particularly on immigration.
"We need different leadership, there isn't a question about it ... I'm worried about our country in the long term," Kasich told ABC's George Stephanopoulus in November.
Flake, on the other hand, has said he will likely not be running for president in 2020. His office did not return a request for comment.
In his farewell speech on the floor of the Senate on Thursday, Flake took a veiled shot at Trump and warned that the U.S. is not immune to authoritarianism.