Sen. John Fetterman is sounding the alarm over socialism’s growing popularity among Democrats, warning that his party is moving away from capitalism as democratic socialists and progressive insurgents score victories in races around the country.

The Pennsylvania Democrat, who has increasingly broken with his party on several high-profile issues, reacted Sunday to a CBS News poll showing a majority of Democratic respondents hold a favorable view of socialism.

According to the poll, 58 percent of Democrats said their opinion of socialism was either “very positive” or “somewhat positive.” Just 18 percent viewed socialism somewhat or very negatively, while 24 percent said they did not have an opinion.

The numbers for capitalism were nearly reversed.

Only 32 percent of Democratic respondents said they viewed capitalism very or somewhat positively. Half said they had a somewhat or very negative opinion of capitalism, while another 18 percent had no opinion.

Fetterman seized on the findings in a social media post Sunday afternoon.

“The Democratic Party is becoming the party of socialism. 58% view socialism positively. 50% view capitalism negatively. I’m a proud free market capitalist. This is lunacy,” Fetterman wrote.

His criticism comes as democratic socialists and insurgent progressive candidates have picked up electoral victories in places including New York, Los Angeles, Michigan and Colorado, adding to a broader debate over the Democratic Party’s ideological direction.

Fetterman has been particularly outspoken about the trend, distancing himself from the party’s socialist wing even as some of its candidates have gained momentum.

In late June, the senator warned about the increasing prominence of what he called the “dirtbag left,” referring to left-wing candidates who have challenged more traditional Democrats while identifying with democratic socialism.

During an appearance with Fox News host Sean Hannity, Fetterman argued that some of the Democrats being targeted by the party’s left flank represented the kind of candidates who would once have been considered mainstream.

“I mean … the kind of people they are trying to run out of office, they are just good, traditional kinds of Democrats you would expect in New York City now,” Fetterman said.

“And now this has just become — really, it’s just been the dancing days of the dirtbag left. You know, some of these candidates are outrageous,” he added.

Fetterman pointed specifically to Democratic nominees who have supported proposals to abolish Immigration and Customs Enforcement, police departments and the border.

His latest remarks underscore an increasingly visible divide inside the Democratic Party. While progressive candidates are finding success with voters in some Democratic strongholds, Fetterman is making clear that he sees the party’s growing embrace of socialism not as a path forward, but as a warning sign.