A former Trump White House lawyer said the evidence against the former president over his handling of classified documents was now “overwhelming” and would “last an antiquity”, after new charges were filed in the case on Thursday.
Related: Trump faces more charges in classified documents case as second aide named
“I think this original indictment was engineered to last a thousand years and now this superseding indictment will last an antiquity,” Ty Cobb told CNN. “This is such a tight case, the evidence is so overwhelming.”
In June, the special counsel Jack Smith indicted Trump on 37 counts regarding his handling of classified records after leaving the White House.
On Thursday, in a superseding indictment filed in a Florida court, four more charges were outlined. A second Trump staffer, the Mar-a-Lago maintenance worker Carlos De Oliveira, was charged, alongside Walt Nauta, Trump’s valet. Nauta previously pleaded not guilty.
Trump was accused of attempting to destroy evidence and inducing someone else to destroy evidence. He also faces a new count under the Espionage Act, for keeping a document about US plans to attack Iran which he famously discussed on tape.
Trump denies all wrongdoing, in the documents case and in other cases including the criminal investigation in New York in which he faces 34 charges relating to hush-money payments to an adult film star.
On Thursday night, on his Truth Social platform, the former president complained about another investigation, of Joe Biden’s own retention of classified material. Trump also called Smith “deranged”.
A spokesperson called the new charges “nothing more than a continued desperate and flailing attempt” by the Biden administration to “harass” Trump and “those around him”.
On Thursday, Trump told the conservative radio host John Fredericks he had handed over security video footage prosecutors now say he ordered deleted.
“These were security tapes,” he said. “We handed them over to them … I’m not even sure what they’re saying.”
Smith is also expected to indict Trump over his attempted election subversion. So are prosecutors in Georgia, regarding the former president’s attempts to overturn his defeat by Biden there.
Found liable for sexual abuse and defamation against the writer E Jean Carroll, and fined around $5m, Trump also faces investigations of his business affairs.
But his legal problems have not dented his popularity with his party. In polling regarding the Republican nomination for president in 2024, Trump has clear leads in early voting states and is approximately 30 points ahead of his nearest challenger, the Florida governor, Ron DeSantis, in national polling.
Trump told Fredericks he will not end his campaign even if he is convicted and sentenced.
“They went after two fine employees yesterday, fine people,” Trump said. “They’re trying to intimidate people so that people go out and make up lies about me. Because I did nothing wrong.”
Cobb represented Trump during the investigation by another special counsel, Robert Mueller, into Russian election interference in the 2016 election and links between Trump and Moscow. The attorney later told the Atlantic he did not regret working for Trump, saying: “I believed then and now I worked for the country.”
On Thursday, he told CNN: “It’s very difficult to imagine how Trump said that his lawyers met with Jack Smith today to explain to him that he hadn’t done anything wrong [Trump’s claim in the election subversion case], on the same day that Jack Smith produces this evidence of overwhelming evidence of additional wrongdoing.
“So this is, I think, par for the course.”
Cobb also said he was sure Trump had been advised by his own lawyers “not to destroy, move [documents] or obstruct this grand jury subpoena in any way.
“So this is Trump going not just behind the back of the prosecutors, this is Trump going behind the back of his own lawyers and dealing with two people” – Nauta and De Oliveira – “who are extremely loyal”.