In an interview broadcast on Sunday, Democratic presidential candidate Joe Biden called President Donald Trump an “idiot,” NBC News reports.

According to Biden, Trump is an “idiot” for dismissing evidence of Russian election interference.

The former vice president said that Trump is, “an idiot — in terms of saying that.”

“Everybody knows this. Everybody knows it. Nobody doubts it,” he added.

According to the Democratic front-runner, not only did Russia meddle in the 2016 presidential election, the country is trying to interfere in the 2020 election as well.

Biden said that the Kremlin has been targeting his campaign, which the commander-in-chief has welcomed.

“The Russians don’t want me to be president and Trump doesn’t want me to be the nominee,” he said, arguing that Trump is not just unwilling to stop foreign election interference, but he is “going out and asking for help” to win re-election.

For months, Trump has been attacking Biden and members of his family. According to the commander-in-chief, the Bidens are corrupt, and the former vice president’s son, Hunter, used his father’s influence to get a seat on the board of a Ukrainian gas company.

According to an anonymous intelligence community whistleblower, Trump pressured the government of Ukraine to investigate the Bidens in order to damage the Democratic front-runner’s White House bid. The president threatened to cut military aid unless Ukrainian authorities fulfill his request, according to the whistleblower.

In response to Trump’s actions, the House of Representatives launched a formal impeachment inquiry. Since the launching of the inquiry, Trump’s attacks on Biden have only become more aggressive, and he continues to claim that all he wanted was to investigate corruption in the eastern European country.

Biden denies any wrongdoing.

According to the former vice president, Trump has “no integrity,” so it comes as no surprise that he is going after his family.

“I’ve never discussed my business or their business, my son’s or daughter’s,” Biden said, asserting that his son did nothing wrong.

“He’s a grown man. And it turns out he did not do a single thing wrong, as everybody’s investigated,” the Democrat said.

Biden is still the Democratic front-runner, according to most polls, but his lead is slowly melting away, it seems, and Massachusetts Senator Elizabeth Warren and Vermont Independent Bernie Sanders appear to be catching up to him.

Furthermore, the former vice president’s campaign had a disappointing third-quarter fundraising haul.

“I know I’m the front-runner,” Biden said, downplaying concerns about his campaign, suggesting that a lot could change until the nominee is selected because the primary race is a “marathon.”