(CNN) Sen. Cory Booker slammed the homeland security secretary in a speech Tuesday morning for claiming ignorance to the President's slander of African countries.

The impassioned remarks came toward the end of an often testy oversight hearing in which Department of Homeland Security Secretary Kirstjen Nielsen denied hearing President Donald Trump say the words "shithole" or "shithouse" in a White House meeting on immigration last week.

Evoking the words of Martin Luther King and the "greatest heroes in this country who spoke out about people who have convenient amnesia or who are bystanders," Booker, a New Jersey Democrat, said Nielsen was complicit in the damage done by Trump's reported insult.

"The commander in chief in an Oval Office meeting referring to people from African countries and Haitians with the most vile and vulgar language, that language festers. When ignorance and bigotry is allied with power it is a dangerous force in our country. Your silence and your amnesia is complicity," Booker said.

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At times visibly upset, Booker said he was "seething with anger" and recalled the "tears of rage" he shed when he first learned of the quote attributed to the President.

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