Trump argues that Kristen Welker, who runs the upcoming debate between him and Biden, is biased, but he will "fight to the end".

"She's always lousy and very biased, like most fake news reporters, but I'm still fighting to the end," US President Donald Trump tweeted on October 18, referring to Kristen Welker, who led

Below the tweet, Trump cites the information that Welker's family has donated tens of thousands of dollars to the Democrats over the years and that the host has attended Christmas at the White House with his family.

"Everybody knows! How's Steve Scully?", Trump added, referring to Scully, who was assigned to lead the second debate between Trump and Biden.

Scully more than a week ago caused controversy by posting a "puzzling" tweet about the President.

Scaramucci once supported Trump, but then opposed the US President and turned to support Democratic presidential candidate Joe Biden.

Many people guessed that the journalist intended to private Scaramucci but had accidentally tweeted it publicly.

Trump's attack on Welker differed from the comment he gave her in January, when the reporter was given a lead on the NBC weekend program.

Jason Miller, Trump's campaign senior adviser, announced last week that Welker is a "very fair man" and will do a great job leading the final debate.

Ms Welker temporarily closed her Twitter account after Scully claimed his account was hacked.

However, colleagues have defended this host.

During the October 17 campaign in Janesville, Wisconsin, Trump also launched attacks against Welker.

This isn't the first time Trump has criticized the presidential debate leader and journalists interviewing him.