Vance walks Trump tightrope with scathing election critique blaming Iran war

Of course, the next presidential election is still two years away. Vance is expected to run but hasn't made an official decision, and aides insist that he's still mulling it over.

It's also up for debate exactly how much Vance broke from Trump. Vance showed the message to Trump before posting it online, according to The New York Times.

Trump, for his part, could change his mind and make clear he'll brook no dissent from Vance or anyone else.

The president has been circumspect about who he'd support to succeed him as the 2028 Republican presidential nominee. Trump has praised Vance and Secretary of State Marco Rubio on several occasions, but hasn't said when - or if – he'd make an endorsement.