Former White House staffer Omarosa Manigault-Newman gave a scathing assessment of Jared Kushner, President Donald Trump's son-in-law and senior advisor, during an interview.

"He's that guy in the room who thinks he's the smartest guy in the room, who has absolutely no idea what's going on," Manigault said, referring to Kusher.

According to Manigault, Jared's performance as a White House official was the defining reason why he was ill-fitted to help shape US policy.

Former White House staffer Omarosa Manigault-Newman offered a scathing assessment of Jared Kushner, President Donald Trump's son-in-law and senior adviser, during an interview on HBO's "Real Time with Bill Maher" on Friday.

"He's that guy in the room who thinks he's the smartest guy in the room, who has absolutely no idea what's going on," Omarosa said, referring to Kushner.

Trump appointed Kushner as his senior adviser in January 2017, following his 2016 US presidential election victory. Kushner, a real-estate investor and businessman, worked closely with Trump throughout the presidential campaign. He has since focused on a broad range of issues — from technological needs, to Middle East policy — in the newly-created Office of American Innovation.

Trump was widely accused of nepotism after giving Kushner and his daughter, Ivanka, who is Kushner's wife, official roles in the White House. But according to Omarosa, Jared's performance was the defining reason why he was ill-fitted to shape US policy.

"He didn't even know basic political jargon," Omarosa said. "And when you try to correct him, he gives you that posture like, are you a woman of color?"

"And so the sad thing about Jared is that he doesn't know how stupid he sounds when he's talking in those meetings," Omarosa added.

After White House chief of staff John Kelly fired Omarosa in December, she published a book chronicling her brief, but intense, tenure in the Trump administration. In "Unhinged: An Insider's Account of the Trump White House," Omarosa describes a chaotic scene in the White House that was reminiscent of her previous appearances on Trump's reality show, "The Apprentice."