Former Secretary of State Hilary Clinton, a prominent Democrat who lost the presidency to Donald Trump in 2016, has warned of one Republican attack on progressive members of her party that will be “very effective” in the midterms.

After progressive Abdul El-Sayed’s victory over centrist congresswoman Haley Stevens in Tuesday’s Democratic primary for a U.S. Senate seat in Michigan, Clinton suggested that Republicans will baselessly label him as a “communist,” and it will work to dissuade voters.

“The real fight will be how do we make sure that people who voted for Haley feel comfortable voting for Abdul El-Sayed, and how do we get Independents to feel comfortable?

“And you can see that it’s not just about Michigan, but the Republican messaging is communist, socialist. It’s going to be a very effective attack,” Clinton told Kara Swisher during the journalist’s Pivot podcast with author Scott Galloway.

Trump was quick to celebrate El-Sayed’s election win, calling it “Great news for the Republican Party.”

“El-Sayed, a Communist loser who hates Jews and Israel, is the projected winner in his race with the Socialist…Now, the Dumocrats crazy policies will only get worse!” he wrote on Truth Social Wednesday.

Despite the pro-Israel group AIPAC spending tens of millions on Stevens’ campaign, El-Sayed — a former public health official who has accused Israel of genocide in its war against Hamas in Gaza — narrowly beat her in Tuesday’s race. Israel has vehemently denied allegations of genocide.

When Swisher probed further on whether labeling a politician a communist is an effective attack, Clinton said, “That’s the attack that Trump is leading with and I assume they’ve tested it and I assume that they have reason to believe that it’s effective or they wouldn’t be beating the drum on it.”

“It’s not just him. [Vice President JD] Vance has done it. Others are doing it. They are trying to bring back scare tactics about our candidates, and it didn’t work in New York. [New York City Mayor Zohran] Mamdani was elected, and there was a lot of money spent against him,” Clinton said.

Mamdani, a democratic socialist who has been commonly misstated as a communist, won his election in November against a member of the Democratic establishment, former New York Governor Andrew Cuomo.

Two democratic socialists whom Mamdani backed in the June primaries in New York, Darializa Avila Chevalier and Claire Valdez, also won their races.