Neera Tanden thinks her former boss Hillary Clinton is still Berned.

The Democratic presidential candidate’s poll number haven’t been the greatest lately, with Republican candidate Donald Trump closing in on her small lead, and Tanden, president of the Center of American Progress, believes Clinton can thank primary opponent Bernie Sanders for her high unfavorability ratings.

In an interview with Politico’s Glenn Thrush posted to YouTube, Tanden said the Vermont senator’s scathing attacks on his opponent have had lasting power.

“This primary … there was much more open attacks on being bought and paid for and all that stuff. Sen. Sanders prosecuted a much … tougher character attack,” she said. “I actually have to say, … I think he brought a lot of really important issues to the fore, but he did do significant damage to Hillary’s negatives. He drove a lot of those negatives.”

“Just to be candid, … I think that getting those kinds of attacks from another Democrat or another liberal or another progressive is much tougher for Hillary, and it was really hard,” said Tanden, who was policy director for Clinton’s failed 2008 presidential campaign before jumping ship to the same role for President Obama after the primary.

Tanden has since worked at the Center for American Progress, where she now serves as president of the Washington, D.C.-based progressive advocacy organization.

During the recent presidential primary Sanders repeatedly called Clinton out for her close ties to Wall Street power brokers, support of the U.S. invasion of Iraq, and advocacy for the North American Free Trade Agreement, which is credited with a mass exodus of jobs from the U.S. to other countries.

Sanders’ portrayal of Clinton as the darling of Wall Street elites – and constant criticism about her failure to release the transcripts of high-dollar speeches to top executives – continues to plague Clinton’s campaign, Tanden told Politico.

“If you look at her trust numbers, the last six months of that primary those numbers took a much sharper dive and it’s been hard to recover from,” she said.

Sanders, of course, isn’t the first liberal to question Clinton’s truthfulness with the American people.

A 2008 Obama primary campaign ad pointed out that “The Washington Post says Clinton isn’t telling the truth,” according to the Daily Kos.

“It was Hillary Clinton, in an interview with Tom Brokaw, who quote ‘paid tribute’ to Ronald Regan’s economic and foreign policy,” the ad said. “She championed NAFTA – even though it has cost South Carolina thousands of jobs. And worst of all, it was Hillary Clinton who voted for George Bush’s war in Iraq.

“Hillary Clinton. She’ll say anything, and change nothing.”

And while Sanders did not attack Clinton for her use of a private email server during her time as Secretary of State that left classified information vulnerable to hackers, her general election opponent has been more than willing to broach the subject.

In fact, he’s devoted an entire website to calling out “Lying Crooked Hillary” for her lies about the private server, as well as lies about the 2012 Benghazi attack and handling of classified materials.

The “Lying Crooked Hillary” site encourages visitors to “sign up now to be notified of the next legendary lie!”