Neera Tanden, the CEO and president of the Center for American Progress (CAP), said Monday that a video published by its affiliated news website, ThinkProgress, criticizing Sen. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (I-Vt.) was "overly harsh."

"The orientation of CAP is to positively engage with all political leaders about the country’s future. ThinkProgress is editorially independent of CAP and CAP Action, which is what has made it valuable as a news outlet," Tanden said in a statement.

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"Similarly, we at CAP can form our own opinions of their work. We believe the content of the ThinkProgress video critiquing Sen. Sanders is overly harsh and does not reflect our approach to a constructive debate of the issues," Tanden added.

Tanden's comments come after Sanders recently accused the liberal think tank of "using its resources to smear" him and other candidates seeking the Democratic nomination for president in 2020.

ThinkProgress, which is run by the Center for American Progress Action Fund, last week published a video criticizing Sanders for being a millionaire and suggesting his stances on income inequality are hypocritical.

Citing the video, Sanders said in a letter to CAP on Saturday that the group has unfairly criticized him. He also accused the think tank of being unfair to fellow 2020 candidates Sen. Elizabeth Warren (D-Mass.) and Sen. Cory Booker (D-N.J.).

“I and other Democratic candidates are running campaigns based on principles and ideas and not engaging in mudslinging or personal attacks on each other," Sanders wrote.

"Meanwhile, the Center for American Progress is using its resources to smear Senator Booker, Senator Warren, and myself, among others. This is hardly the way to build unity, or to win the general election," he added.

CAP responded Sunday by saying it will not "muzzle" the journalists at ThinkProgress.

"Indeed, ThinkProgress publishes articles with which we disagree," the group said. "We cannot and will not muzzle ThinkProgress, an editorially independent journalistic enterprise, and we believe it’s wrong for any political leader to demand it do so."