Democratic presidential nominee Joe Biden speaks as he participates in the first 2020 presidential campaign debate with U.S. President Donald Trump held on the campus of the Cleveland Clinic at Case Western Reserve University in Cleveland, Ohio, September 29, 2020.Brian Snyder | ReutersWASHINGTON – Democratic presidential nominee Joe Biden is ready for President Donald Trump to unleash a torrent of attacks on Biden’s family Thursday night at the final presidential debate, Biden campaign aides said.”We expect that Trump will attack Vice President Biden and his family,” said deputy campaign manager Kate Bedingfield on a pre-debate conference call. “Every time he does that, all he’s doing is reinforcing what we have said all along: He is acknowledging that he has no case for a second term.”Down in the polls with 12 days to go, Trump has seized on recently released emails allegedly taken off a laptop belonging to Biden’s son Hunter. The emails have not been independently verified.Intelligence analysts say that the timing of their release, and their murky provenance, bear the hallmarks of Russian election interference.Trump, nonetheless, has demanded repeatedly this week that Biden be prosecuted for unidentified crimes. Earlier this week a reporter asked Trump what exactly he was claiming Biden had done wrong. Trump replied simply: “He is a criminal. He’s a criminal…. Let me tell you something: Joe Biden is a criminal, and he’s been a criminal for a long time.””These attacks are backfiring on Trump,” said Bedingfield. “Voters are sick and tired of Trump’s lies, and we’ve heard the same debunked attacks for over a year.”Trump and his lawyer Rudy Giuliani have spent more than a year trying to sow suspicion that Biden used his position as vice president to help his son’s business ventures in Ukraine. But a Republican-led Senate probe earlier this year found no wrongdoing on Biden’s behalf.Biden has stayed out of the spotlight most of the week, preparing for the high stakes debate in Nashville.The narrative of secret emails released just weeks before a presidential election in an attempt to damage the opponent of Donald Trump is a familiar one. In 2016, Russian intelligence units hacked the Democratic National Committee and released emails intended to damage then-Democratic nominee Hillary Clinton.Bedingfield said it’s no secret that Russia and other foreign countries are seeking to interfere with the U.S. election. “What’s most troubling is that Donald Trump and his campaign seem perfectly comfortable using what many believe to be foreign attempts at interference for their own political gain,” she said.This is likely to be the centerpiece of Biden’s rebuttal against Trump’s attacks. Firstly that there’s no “there” there. But more importantly, that Trump is once again using the product of suspected Russian interference to try and smear his opponent days away from an election.”I think the contrast here is incredibly strong,” said Bedingfield. “In Joe Biden, you have somebody who has said unequivocally that foreign interference in our elections is not something he will tolerate, not something he would tolerate if he were president. And you can’t say the same for Donald Trump.”Following the Biden call, the Trump campaign held its own pre-debate call.That call was focused solely on recent allegations against the Bidens, and the campaign participants refused to answer any questions outside of that subject.When NPR’s Tamara Keith attempted to ask about Trump’s debate preparations, Ambassador Richard Grenell responded, “Have you reported on the Biden emails?”Keith replied that she covers the Trump campaign, not the Biden campaign. When Grenell began to press the issue, Keith cut in to note that she has colleagues who have covered the allegations.”I’m speaking, I’m speaking. Don’t be homophobic,” said Grenell, who is gay. “Don’t interrupt, don’t interrupt, don’t interrupt. I’m speaking.”The 90-minute debate will air across broadcast TV and cable news stations starting at 9:00 p.m. ET.– CNBC’s Kevin Breuninger contributed to this article.