Breitbart chair Steve Bannon gave President Trump’s Democratic enemies ammunition to attack the Trump administration by bashing Trump and his family members in a new book.

Bannon criticized the president, his oldest son (Donald Jr.), his daughter Ivanka and her husband Jared Kushner in interviews for Michael Wolff’s new book about the president, “Fire and Fury.” Bannon is quoted calling Ivanka “dumb as a brick” and attacked Kushner and Donald Jr. as “treasonous” for meeting with a Russian lawyer who said she had dirt on Hillary Clinton during the campaign.

Bannon’s attacks on Trump’s family have given Democrats new ammunition to attack the president.

House Democrats, who have been looking for a reason to prolong the House Intelligence Committee’s leaky Russia probe, seized on Bannon’s comments about Don Jr. and Kushner to do exactly that.

California Rep. Ted Lieu immediately called on congressional committees to subpoena Bannon for testimony as a result of his comments about Don Jr. and Kushner. “Based on the statements by Steve Bannon, congressional committees now need to subpoena him to testify on the #TrumpRussia investigation,” Lieu wrote on Twitter.

California Rep. Eric Swalwell, a top Democrat on the intel committee, similarly used Bannon’s comments to argue that the House investigation, which has turned up no evidence of collusion, needs to continue longer.

“You have to be asking yourself if you’re a House Republican, how far off is your moral compass if Steve Bannon is identifying a Trump-Russia relationship as one that is unAmerican and you’re arguing the other way,” Swalwell said on CNN Wednesday evening.

Swalwell said that House Democrats will seek Bannon’s testimony as part of the Russia probe, which House Republicans have said is close to wrapping up.

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The president and his family returned fire on Bannon after his comments surfaced on Wednesday. Trump accused Bannon of helping Democrats win the Alabama special election by boosting Roy Moore during the GOP primary. Bannon was one of Moore’s earliest supporters before his embarrassing loss to Alabama Democrat Doug Jones. (RELATED: WSJ Suggests Bannon Wants Republicans To Lose The Senate)

“Steve had the honor of working in the White House & serving the country. Unfortunately, he squandered that privilege & turned that opportunity into a nightmare of backstabbing, harassing, leaking, lying & undermining the President,” Donald Jr. wrote on Twitter. “Steve is not a strategist, he is an opportunist.”