Would-be Donald Trump assassin Ryan Wesley Routh pleaded not guilty to charges related to his alleged attempt to take the former president’s life while Trump was golfing in Florida earlier this month.

Routh, 58, appeared in federal court in Fort Pierce, Fla., Monday on fresh charges accusing him of lying in wait for 12 hours in the hedges of Trump International Golf Club in West Palm Beach with an assault rifle on Sept. 15.

Routh — handcuffed and wearing tan jail clothes — took his glasses on and off during the short hearing as Magistrate Judge Bruce Reinhart asked if he understood the charges he faced.

“Yes, your honor,” Routh said, before his lawyer entered the not guilty plea on his behalf.

A Secret Service agent foiled the plot when he spotted the muzzle of Routh’s gun through a fence and opened fire. Routh did not squeeze off any shots.

Routh, a roof contractor from Hawaii, fled the hideout positioned near the sixth hole but was caught soon after on a highway, according to prosecutors.

Law enforcement found an AK-47-style SKS semi-automatic rifle equipped with a scope and an extended magazine left behind, the feds claim.

Routh, originally from North Carolina, also left behind a GoPro camera, metal plates for protection from potential gunfire from the Secret Service and snacks, prosecutors allege.

The alleged gunman was initially only hit with weapon possession charges, but a day after the feds released a letter he wrote admitting he planned to kill Trump, he was also slapped with assassination attempt charges.

“This was an assassination attempt on Donald Trump but I failed you,” the eerie letter read.

“I tried my best and gave it all the gumption I could muster. It is up to you now to finish the job; and I will offer $150,000 to whomever can complete the job.”

His defense attorneys said at a Sept. 23 court hearing that he might have penned the letter — which he left with an unidentified associate — to shine a public spotlight on his advocacy for democracy in Ukraine and Taiwan.

A judge ordered that Routh remain behind bars pending trial at that hearing.

Routh faces charges of attempted assassination of a major presidential candidate, possessing a firearm in furtherance of a crime of violence, assaulting a federal officer, possession of a firearm and ammunition and possession of a firearm with an obliterated serial number.

Routh’s trial has been randomly assigned to Judge Aileen Cannon, a Trump appointee who in July dismissed criminal charges against the ex-commander-in-chief for allegedly hoarding troves of classified documents at his Mar-a-Lago estate after leaving office.

Cannon ruled that Jack Smith’s appointment as special counsel in the case violated the Constitution, a decision which Smith’s office is appealing.

Routh faces up to life in prison if convicted on the top charge.

The assassination attempt in the Sunshine State is the second in less than two months. Thomas Matthew Crooks shot and injured the 45th president during a campaign rally in Butler, Pa., in July. One of the bullets grazed Trump’s ear before a Secret Service sniper fatally shot the gunman.

Routh has two prior convictions in North Carolina for getting caught with a bomb in a police standoff and for possession of stolen goods.

His son, Oran Routh, was arrested Sept. 24 for child pornography charges in an unrelated case after the feds searched his home and allegedly found hundreds of sick images on his devices. Oran is expected to appear in a North Carolina federal court Tuesday in that case.

With Post wires