Joshua Kerry, 28, of Rotherham, South Yorkshire, was charged on Friday with one count of preparation of terrorist acts.
The charge relates to alleged activity between 31 May 2024 and 8 July 2026.
Kerry is due to appear at Westminster Magistrates' Court on 7 October.
He is also accused of the murder of Ms Widdecombe.
The Reform UK spokeswoman and former Tory minister, 78, died on 8 July after she was hit over the head with a hammer 21 times at her home in Haytor on Dartmoor, Devon, a court previously heard.
Kerry was charged with her murder on 20 July.
Deputy Assistant Commissioner Vicki Evans, senior national coordinator for Counter Terrorism Policing, said on Friday: "We have been running a hugely intensive and complex investigation for some time.
"The charge announced today is a result of the tireless work of investigators across the Counter Terrorism Policing network.
"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."
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Chief crown prosecutor Frank Ferguson, of the Crown Prosecution Service's Special Crime and Counter Terrorism Division, said: "Having carefully reviewed the evidence, we have made the decision to prosecute Joshua Kerry for engaging in conduct in preparation of terrorist acts."
He said prosecutors "have worked closely with police to establish that there is sufficient evidence to bring this case to court, and we will continue working with them as their investigation progresses".
Salam Ahmadyan, 36, of Liverpool, and Rahman Salehi, 34, from Salford, were arrested by counter terror police in Manchester on 20 September.
Both suspects have been charged with preparation of terrorist acts over an alleged plot to target the Jewish community in the Manchester area.
Both suspects came to the UK on small boats several years ago, Home Secretary Shabana Mahmood said.
It is understood the two men arrived in 2020 and 2023, with one granted asylum, while the other has a live asylum claim.
The allegations relate to offences ahead of the festival of Yom Kippur - widely considered the holiest day in the Jewish calendar - Counter Terrorism Policing said.
The charges allege the defendants tried to get components for a homemade bomb, including a manual on how to make an explosive device out of chlorine and brake fluid.
It is also alleged that the two men were in contact with an overseas third party who may be in Iran in relation to the plot, CTP said.
Deputy Assistant Commissioner Vicki Evans, senior national coordinator for Counter Terrorism Policing (CTP), said: "These are extremely serious charges and allegations.
"This investigation has led to the disruption of what we believe to have been a plot targeting the Jewish community in Manchester.
"I would like to reiterate that we do not believe there to be any ongoing threat to the public in relation to this matter, but as always, we would ask that people remain vigilant and contact police with any concerns."
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Both men have been remanded in custody to appear at Westminster Magistrates' Court on Saturday.
Salehi and Ahmadyan are alleged to have intended to commit acts of terrorism, or assist another to commit acts on or before 20 September.
This includes communicating with others using encrypted apps to get components to assemble a homemade explosive device.
They are also charged with trying to get hold of a document entitled "steps for making a powder chlorine and car brake oil/fluid bomb".
The charges state they tried to "acquire video material containing instructions on how to manufacture or assemble an improvised explosive device" and that they tried to "acquire liquids, components and equipment required to manufacture or assemble an improvised explosive device".
It also alleges they used "the internet to identify and research potential targets for attack, acquired images, plans and maps of potential targets for attack and conducted reconnaissance of potential locations for attack".
As part of the investigation, searches at homes in Liverpool and Salford were carried out, police said.
Frank Ferguson, chief crown prosecutor for the CPS's Special Crime and Counter Terrorism Division, said prosecutors have decided "there is sufficient evidence to bring this case to court" while reminding people that, with legal proceedings active, online commentary should be avoided.
He added: "We want to assure the Jewish community that working with the police, their safety and that of the wider public is our highest priority."
Hospital staff were working to save her life and clear two doses of the drug the state uses to execute prisoners, they added.
In a court filing, Pike's legal team said problems with the IV lines caused the lethal drug pentobarbital to go into her body, instead of her bloodstream.
They wrote: "Apparently at no point did any member of the execution team realise that the IV lines were not correctly placed or that the veins had blown and that the pentobarbital was, in whole or in part, entering Ms Pike's body."
Instead of "remedying this failure", they prepared and administered a backup set of pentobarbital syringe, the lawyers added.
The execution team worked for an hour to administer the lethal drugs, said Pike's defence lawyer Randy Spivey, who counted at least seven needles in her left arm.
She was still snoring when the execution chamber's microphone was cut off more than an hour into the execution attempt.
"Preserving this evidence is essential to understanding what happened, ensuring accountability and protecting Christa's legal rights," two of her lawyers said in a statement.
State officials have not offered any explanations about what went wrong.
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Tennessee Governor Bill Lee ordered a review of the state's execution procedures and indefinitely postponed Pike's execution and another one slated for this year.
Pike, 50, has suffered significant injuries to both her arms, her lawyers have said, and is in a critical condition following the failed execution on Wednesday.
She was taken by ambulance from Riverbend Maximum Security Institution in Nashville.
Maya Martinez, the mother of Colleen, expressed frustration over the failed execution, saying on Thursday: "I didn't get justice for my daughter."
Pike was convicted of killing her 19-year-old classmate Colleen Slemmer in 1995, when she was 18.
Following the killing, Pike was diagnosed with bipolar disorder and post-traumatic stress disorder, her lawyers said.
She had been scheduled to be the first woman executed in Tennessee in more than two centuries.
It comes after the 31-year-old England cricketer was arrested on suspicion of being drunk and disorderly following an incident at a Derby nightclub this summer.
The charge, which follows an investigation by the Cricket Regulator, refers to events on 23 August when Carse was handcuffed by police officers after a celebratory night out with his Durham teammates.
He was "de-arrested" later after agreeing to leave.
Derbyshire Police had said they were investigating an alleged assault in connection with the incident but in September they said there would be no further action taken.
The Cricket Regulator said in a statement on Friday: "Following a Cricket Regulator investigation, Brydon Carse has been charged with breaching regulation 3.2 of the ECB professional conduct regulations, in relation to events in Derby in the early hours of the morning on 23rd August 2026."
The incident will be now be referred to the independent Cricket Discipline Panel for adjudication, the regulator said, adding that "as the process is ongoing, no further comment will be made".
Regulation 3.2 warns against conduct "which is improper or which may be prejudicial to the interests of cricket or which may bring the ECB, the game of cricket or any cricketer or group of cricketers into disrepute".
Carse was dropped for England's second and third Tests against Pakistan in the wake of the incident and was left out of the squad for last month's limited-overs contests against Sri Lanka.
England captain Joe Root said he was "hacked off" by the affair, as team discipline was already under scrutiny following similar events.
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Carse was also left out of England's 16-man party for this month's one-day international tri-series against Pakistan and Sri Lanka.
Carse continued to play for Durham during the summer and helped the side earn promotion to the first division of the County Championship.
Zara Shaw and Luke Etheridge, both 16, died when the vehicle went into the water near Wearmouth Bridge in Sunderland, on Tuesday. Jackson Duke, 17, also died in the incident.
A black Audi A3 careered off the road at Panns Bank before entering the water shortly before 1.30pm on Tuesday, police said.
A 17-year-old boy who was also in the car "reached safety" and suffered non-serious injuries, Northumbria Police said.
He was arrested on suspicion of causing death by dangerous driving, and has since been released on bail pending further inquiries.
On Friday, Zara's family issued a statement which said: "Zara, you came into this world with a fight, and we know you left it doing the same.
"You had a zest for life and life loved you. Created as a companion for your sister, Olivia, who loves you deeply and unconditionally.
"You made us proud from day one, you studied and learnt new skills and made lifetime friends.
"Having fun along the way with your dance videos, infectious laugh and smile, you have always been our beloved daughter, sister, granddaughter, niece, cousin, girlfriend and best friend."
Luke's family described how the football-mad teenager was Sunderland's "number one fan" and how he loved his dog, Wilf.
They said: "Our beautiful boy Luke was loving, kind, caring, funny and handsome.
"He was so friendly and polite and loved our dog Wilf, shopping for clothes, watching and playing football.
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"He always knew the most up-to-date Sunderland football news and shared it with us immediately.
"As a family we did everything together from football to holidays, shopping trips and spending time with Wilf our dog.
"Luke is our life, we miss him so bad. Our hearts will ache forever."
Jackson and Luke were from the Sunderland area, and Zara was from Houghton-le-Spring in Tyne and Wear, the force said.
Investigations into what led up to the car entering the water, and to establish who was driving at the time, are ongoing, but no other vehicles are believed to have been involved, police said.