Rubio knocks Tillerson's opposition to regime change: 'There is no such thing as "Assad yes, but ISIS, no."'
In an interview on "This Week," Rubio said he did not intend to "pick a fight with anyone here," but that Tillerson's strategy was "based on assumptions that aren't going to work."
"There seems to be a difference between what Ambassador Haley is saying, as she said last night, that Assad really has no future, and what I heard this morning from Secretary Tillerson," Rubio said.
He added: "There is no such thing as 'Assad yes, but ISIS, no.' This theory that you can defeat ISIS as long as Assad is there is not true. They're two sides of the same coin."
The Florida senator, a longtime proponent of deposing Assad, argued that there cannot be peace in Syria "as long as Bashar Assad is in power."
"The quicker they realize that, the better our strategy is going to be," he said.
Late last month, both Haley and Tillerson said separately that the US was not committed to removing Assad.
But after the Syrian president used chemical sarin gas during a fight with rebels on Tuesday, Haley has taken a stronger line against Assad.
"Getting Assad out is not the only priority," Haley told CNN on Sunday. "And so what we're trying to do is obviously defeat ISIS. Secondly, we don't see a peaceful Syria with Assad in there."
"Regime change is something that we think is going to happen because all of the parties are going to see that Assad is not the leader that needs to be taking place for Syria," she said. "So what I think you're seeing is, this isn't about policy or not, this is about thoughts. And so when you look at the thoughts, there is no political solution that any of us can see with Assad at the lead."
Tillerson appeared to echo President Donald Trump's previous opposition to pursuing regime change, telling ABC that there was no change in US policy from last month.
"We've seen what that looks like when you undertake a violent regime change in Libya and the situation in Libya continues to be very chaotic and I would argue that the life of the Libyan people is not all that well off today," Tillerson said. "So I think we have to learn the lessons of the past and learn the lessons of what went wrong in Libya when you choose that pathway of regime change. ... Any time you go in and have a violent change at the top, it is very difficult to create the conditions for stability longer term."
Despite turning down reported offers to serve as Trump's secretary of state, Haley has emerged as the administration's top spokesperson on foreign policy issues.
While Tillerson and his state department shunned the press, Haley has sat down with the major television programs, and delivered speeches to the UN that cable news stations carried live. She has also reassured key allies, and been more outspoken in criticizing Russia than her Washington counterpart, who has a longstanding relationship with Russia's President Vladimir Putin.
Politico reported last week that Haley may be poised to inherit the job from Tillerson later in the administration.