Ryan Routh, 58, was already facing two gun-related charges after authorities said he pointed a rifle through a fence at Trump’s golf club in West Palm Beach, Florida on September 15 this year while the Republican presidential candidate was golfing there.
He has been ordered to remain in jail to await trial.
"The Justice Department will not tolerate violence that strikes at the heart of our democracy, and we will find and hold accountable those who perpetrate it. This must stop,” Attorney General Merrick Garland said in a statement.
The Department of Justice said a federal grand jury in Miami returned the indictment on Tuesday afternoon. The attempted assassination charge carries a maximum sentence of life in prison.
The case has been assigned to US District Judge Aileen Cannon, who dismissed a criminal case in July accusing Trump, who was President from 2017 until 2021, of illegally keeping classified documents after leaving office.
Routh has not yet entered a plea. His lawyers unsuccessfully sought to have him released on bond.
Prosecutors have in recent days revealed evidence they said pointed toward a plan to kill Trump.
They alleged that months before the incident, Routh dropped off a letter to an unidentified person alluding to “an assassination attempt on Donald Trump.”
They said Routh spent a month in South Florida and cell phone data showed him near the golf course and Trump’s Florida residence at Mar-a-Lago.
He was found with a handwritten list of dates and venues where Trump spoke or was expected to appear, according to court filings.
A US Secret Service agent searching the golf course ahead of Trump opened fire after discovering the gun poking through the fence, causing Routh to flee, prosecutors said.
He was arrested within an hour along a Florida highway.
Routh was initially charged with possession of a firearm as a convicted felon and possession of a firearm with an obliterated serial number.
