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Sen. Sherrod Brown (D-Ohio) has some thoughts about the race he ruled out.

Brown, a progressive who easily won re-election while the rest of his state went red in 2018, opted out of a presidential run despite even his barber encouraging him to do it. Yet he has a word of caution for the Democrat he eventually wants to win his state, and it's a rule several of the candidates have already violated, he tells CNN.

"I think it's a terrible mistake if the Democratic nominee would publicly support Medicare-for-all," Brown told CNN ahead of Tuesday's Democratic primary debate. He said that promise would scare off voters who fear losing their health care, and instead encouraged the eventual nominee to promise Affordable Care Act expansion instead. Backing the progressive policy could cost the eventual nominee Ohio, Brown said — a state he emphasized went to the winner in every election since former President John F. Kennedy's.

Of course, Brown's advice is already worthless to some of 2020's top contenders. Sen. Elizabeth Warren (D-Mass.) has already made it clear that she's "with" Sen. Bernie Sanders (I-Vt.) on the Medicare-for-all bill he wrote. Former Vice President Joe Biden, on the other hand, is very blatantly with Brown on this one.