Much like Donald Trump , former Exxon Mobil CEO Rex Tillerson the Republican president-elects choice for secretary of state appears well on his way to making Sen. John McCain s (R-Ariz.) blacklist.

Asked by reporters Wednesday if he would support Trumps nomination of the oil tycoon, a friend of Russia , McCain quipped: Sure theres also a realistic scenario that pigs fly .

McCain stopped shy of promising to vote against Trumps pick for Americas top diplomat, and his spokeswoman Rachael Dean later clarified that her boss was joking with his comment.

He has repeatedly said that he has concerns regarding Mr. Tillersons nomination, but has made no decision, she wrote in an email.