Former US President Donald Trump will be formally charged at a court hearing on Thursday on charges of plotting to overturn his 2020 election defeat.
On the eve of the arraignment he slammed the case as proof of the “corruption, scandal, & failure” of the US under Joe Biden’s presidency.
Security is being ramped up in Washington DC for Thursday’s hearing.
Mr Trump already faces two other criminal cases as he campaigns for the White House next year.
But the election case is widely seen as the most serious one of all.
In an all-capital-letters post on his Truth Social platform on Wednesday, Mr Trump, who was at his Bedminster, New Jersey, golf club, thanked his followers and said: “I never had so much support on anything before.”
In other posts he attacked rival Republican presidential hopefuls, including his former Vice-President Mike Pence and Florida Governor Ron DeSantis.
He repeated his argument that Mr Pence had had the legal authority to stop Congress from certifying Mr Biden’s election victory on 6 January 2021, proceedings that were disrupted as Trump supporters rioted at the US Capitol.
Mr Trump, 77, is due to appear at a federal courthouse in Washington DC on Thursday at 16:00 EDT (20:00 GMT). He is expected to plead not guilty. Although he has the option of appearing remotely via video feed, it is understood he will attend in person.
Mr Trump has visited the city only once since leaving the White House. A queue was already forming on Wednesday evening outside the building.
In the indictment unsealed on Tuesday, he faces four counts, including conspiracy to defraud the US, tampering with a witness and conspiracy against the rights of citizens.
The deprivation of rights statute was enacted in the aftermath of the US Civil War to provide legal protections for freed slaves as they integrated into society.
The charge was key to a 1967 trial of Ku Klux Klan members that inspired the 1988 film Mississippi Burning. Legal analysts say it has been included in the case against Mr Trump because his alleged efforts to subvert the vote targeted urban areas with large populations of African-American voters.
Attorney John Lauro appeared on NBC’s Today show on Wednesday and said he planned to argue that Mr Trump was protected by the right to free speech enshrined in the First Amendment of the US Constitution.