Joshua Kerry, 28, who is already charged with the murder of Ann Widdecombe, has been charged with preparing acts of terrorism, including an alleged plot targeting Reform UK leader Nigel Farage.
Counter Terrorism Policing announced on Friday that Kerry faces one count of preparation of terrorist acts. The charge relates to alleged activity between May 2024 and July 2026.
Kerry was charged in July with the murder of Widdecombe, 78, a former Conservative minister and Reform UK spokeswoman. She was found dead on 9 July at her home in Haytor, Devon, having sustained serious injuries.
Counter Terrorism Policing Deputy Assistant Commissioner Vicki Evans described the latest charge as the result of a "hugely intensive and complex investigation."
"This investigation has been led by a dedicated team of detectives, analysts, and forensic experts, working on multiple lines of enquiry, which has resulted in this very serious charge," she said.
Kerry is due to appear in court over the terror charge on Wednesday.
Frank Ferguson of the Crown Prosecution Service's Special Crime and Counter Terrorism Division said prosecutors "worked closely" with police to bring the charge and would continue to work alongside them as the investigation continued.
Widdecombe served as Conservative MP for Maidstone in Kent for 23 years and held ministerial roles in Sir John Major's government during the 1990s. After leaving the Commons, she appeared on the television programme Strictly Come Dancing before becoming a Reform UK spokeswoman.