Marco Rubio speaks on March 12, 2016, regarding his increasing unease about supporting Donald Trump if Trump is nominated for president. MSNBC A visibly pained Marco Rubio told reporters Saturday morning that he doesn't know whether he'd be able to support Donald Trump if the Republican frontrunner wins their party's presidential nomination.

A day after chaos erupted at Trump's Chicago rally, Rubio said he's concerned that the real-estate magnate is feeding civil unrest, leading the country to "chaos" and "anarchy."

"You wonder if we're headed in a different direction today where we're no longer capable of having differences of opinion but in fact now protests become a license to take up violence and take on your opponents physically," Rubio said Saturday. "This is what happens when a leading presidential candidate goes around feeding into a narrative of bitterness and anger and frustration."

This is a valid concern — but Rubio is as much to blame for it as Trump is.

Remember, Rubio is the candidate who says President Barack Obama is "undermining this country" as "part of a plan to weaken America on the global stage." Rubio says of Obama that "all this damage that he's done to America is deliberate." He attacked the president's choice to speak at a mosque as an example of his "constant pitting people against each other," which is "hurting our country badly."

Last month, when CNN asked Rubio's spokesman Alex Conant whether the senator believes Obama is "intentionally trying to destroy the country," Conant said "absolutely."

So who, exactly, is feeding into the narrative of bitterness, anger, and frustration?

This is an aspect of Trumpism that establishment Republicans like Rubio have failed to reckon with. They have spent seven years running around the country, accusing the president of being a fifth columnist hell bent on destroying our country. If Obama's America were as bad as people like Rubio say it is, the civil unrest fomented by Trump would be justified.

Now the Republicans who fed this narrative are watching in apparent horror as they see voters have taken them all too seriously.

Rubio says the idea of supporting Trump as the nominee is "getting harder every day." Given the look on his face Saturday morning, I believe he may not be able to bring himself to do it. But to withhold his support from Trump, he would have to admit that the prospect of another Democratic administration is not as horrible as he has said all along.

"I think we all need to take a step back and ask whether we're contributing to this," Rubio said Saturday about the unrest. He should start with himself.

Rubio's Saturday-morning press conference can be seen below: