On Friday, the former president appeared on Gab – a social media site that has become popular with the political right – to make his first post in a while. He used the post to blast his upcoming impeachment trial.
The new post showed a copy of a letter by Trump lawyers Bruce Castor and David Schoensen to Congressman Raskin of the House Impeachment Counsel.
The letter reads: “We are in receipt of your latest public relations stunt. As you certainly know, there is no such thing as a negative inference in this unconstitutional proceeding.
“Your letter only confirms what is known to everyone: You cannot prove your allegations against the 45th President of the United States, who is now a private citizen.”
It comes after Mr Raskin sent Mr Trump a letter of his own requesting that he testify at the trial, which is due to begin on Tuesday.
Mr Trump has been accused of “incitement of insurrection” due to comments he had made leading up to the violent protests which hit the US Capitol on January 6.
If he is convicted after a trial, the former US president could face being banned from ever running for the presidency again.
Mr Trump’s post on Gab was his first on social media since January 8, when he confirmed he would not be attending the inauguration ceremony of Joe Biden.
On the same day, Twitter announced it was permanently ban Mr Trump from its platform, citing “risk of further incitement of violence”.
Mr Trump had used Twitter to repeatedly claim the results of the US election last November were fraudulent.
The claims remain unsubstantiated.