Joe Biden called it “improper” for President Donald Trump for having his daughter and son-in-law hold positions in the White House, suggesting in a CBS interview Sunday that Jared Kushner is not qualified to weigh in on the complex affairs assigned by his father-in-law.

That assessment, which the Democratic presidential hopeful offered in a wide-ranging “60 Minutes” interview, ratchets up the rhetoric between Trump and Biden over each other’s adult children and family business affairs.

Biden told CBS that he doesn’t like “going after” politicians’ children, but he said none of his children would hold White House posts, even as he continued to defend his son, Hunter, against Trump’s charges that the Biden’s are corrupt because of the younger Biden’s international business affairs while his father was vice president.

“You should make it clear to the American public that everything you’re doing is for them,” Biden said, according to a CBS transcript, when he was asked about Ivanka Trump and Kushner, her husband, in White House posts with significant policy portfolios.

“Their actions speak for themselves,” Biden said of the Trump family. “I can just tell you this, that if I’m president get elected president my children are not gonna have offices in the White House. My children are not gonna sit in on Cabinet meetings.”

Asked specifically whether he thinks Kushner should be tasked with negotiating Middle East peace agreements, Biden laughed. “No, I don’t,” he said. “What credentials does he bring to that?”

Hunter Biden’s work in Ukraine and China remains an emphasis of Trump’s broadsides against Biden, a front-runner for the Democratic presidential nomination. The younger Biden took a post on the board of a Ukrainian energy firm after his father became the Obama administration’s point man on U.S.-Ukraine relations.

Trump’s focus on finding information about the Biden’s Ukraine connections is now at the heart of a House impeachment inquiry against the president. Ukrainian investigators have found no legal wrongdoing by either Biden.

Noting that, the former vice president blasted social media giant Facebook for allowing the Trump campaign to distribute online ads framing the Bidens as corrupt.

“You know, I’m glad they brought the Russians down,” Biden said, noting Facebook’s recent decision to shut down accounts that were distributing misinformation, including about Biden. But, the former vice president asked, “Why don’t you bring down the lies that Trump is telling and everybody knows are lies?”

Hunter Biden in a recent interview said the only thing his father said to him at the time he took the post at Burisma was, “I hope you know what you’re doing.”

The elder Biden told CBS he never got into any details over the firm, which had been the focus on Ukrainian corruption inquiries.

“What I meant by that is I hope you’ve thought this through. I hope you know exactly what you’re doing here,” the elder Biden said. “That’s all I meant. Nothing more than that because I’ve never discussed my business or their business, my sons’ or daughter’s. And I’ve never discussed them because they know where I have to do my job and that’s it and they have to make their own judgments.”

And turning the issue back on the president, Biden repeated a line he’s started using on the campaign trail, urging Trump to release his tax returns. “Mr. President … let’s see how straight you are, okay old buddy?” Biden said. “I put out 21 years of mine. You wanna deal with corruption? Start to act like it. Release your tax returns or shut up.”

Trump’s attacks have not displaced Biden as a duel Democratic front-runner alongside Sen. Elizabeth Warren. But it has nonetheless raised new questions about Biden’s argument that he’d be the best Democrat to take on the Republican president in a general election. And the Biden attack ads Trump and Republicans have financed in early nominating states, combined with Biden’s own lagging fundraising, have led some of his wealthy supporters to openly discuss the possibility of launching an independent political action committee.

Biden’s CBS interview was taped before his recent decision to reverse his previous opposition to such a Super PAC, a move that Warren and Sen. Bernie Sanders have indirectly criticized. Biden did address his campaign’s cash balance being dwarfed by Warren and Sanders, saying he’s “not worried” about raising enough money.

As to just how he can withstand Sanders’ and Warren’s grassroots fundraising juggernauts, he replied, “I just flat beat them.”