Julian Zelizer, a professor of history and public affairs, warns that right-wing Democrats (who are labeled as ‘moderates’ and ‘centrists’ by the right-wing mainstream media) should realize that the critiques of their progressive rivals are feeding into right-wing talking points.

As the Democratic caucuses and primaries heat up, the candidates are starting to go after each other with greater ferocity. Sensing a potential victory in Iowa, Mayor Pete Buttigieg launched an ad that goes after proposals from Sens. Elizabeth Warren and Bernie Sanders to make tuition free at public colleges and universities.

“I believe we should move to make college affordable for everybody,” Buttigieg says in the ad. “There are some voices saying, ‘Well that doesn’t count unless you go even further, unless it’s free even for the kids of millionaires. But I only want to make promises that we can keep.”

The mayor’s critics have pounced on this line of attack. After all, some of the nation’s most successful federal programs — such as Social Security, Medicare and K-12 public education — have been available to all Americans regardless of their income. Surely, he doesn’t think that these programs are also misconceived?

New York Rep. Alexandria Ocasio Cortez weighed in with a warning on Twitter: “This is a GOP talking point used to dismantle public systems & it’s sad to see a Dem candidate adopt it. Just like rich kids can attend public school, they should be able to attend tuition free public college.”

To be sure, it is more than legitimate for Democrats to attack proposals from their competitors as too bold or poorly conceived. It is healthy for Democrats to encounter tough criticism from every quarter to see who is best prepared to take on President Donald Trump in 2020.

But Democrats need to be cautious. There is a long history of Republican candidates using smears that unfairly characterize candidates or their policies against the Democratic party nominee. Very often the candidates who think of themselves as the most moderate in the bunch find themselves the target of rhetoric that they or one of their colleagues originally produced.

Democratic candidates who seek to paint themselves as the most moderate in the pack should not forget just how far the GOP is willing go to paint any of the nominees as wild-eyed socialist radicals. Democrats should not underestimate the importance of working as a party to frame the debate around key issues so that they don’t end up giving bipartisan legitimacy to spurious conservative talking points.

He goes on to provide example after example of how Republicans in the past have taken these statements by so-called centrists to attack the eventual nominee, whoever it turned out to be, and concludes:

Democrats who attack from the center don’t always think through the potential impact of their words. They operate from a mythical position that they will be able to insulate themselves from the same such attacks if their turn comes in the crossfire. But we have seen from history it doesn’t work that way.

Buttigieg’s shtick of smugly saying “Look at me, I’m the sensible Democrat” is wearing thin as he increasingly drifts towards regurgitating Republican talking points.