A man suspected of attempting to assassinate Donald Trump has been charged with two federal gun-related offenses after being found with a rifle concealed in the bushes at the former US president's Florida golf course, Reuters reported.

According to a criminal complaint filed on Monday, phone records indicate the suspect may have been waiting for nearly 12 hours, equipped with a rifle and supplies.

While additional charges are anticipated, the current charges—being a convicted felon in possession of a firearm and possessing a firearm with an obliterated serial number — enable authorities to hold him while the investigation proceeds.

Trump, the Republican presidential candidate in the November 5 election, was unharmed. But the incident raised fresh questions about how an armed suspect was able to get so close to him, just two months after another gunman fired at Trump during a July 13 rally in Butler, Pennsylvania, grazing his ear with a bullet.

The US Secret Service opened fire after an agent saw a rifle barrel poking out of the bushes on Sunday at Trump's golf course in West Palm Beach, a few hundred yards away from where the former president was playing.

The gunman fled in a sports utility vehicle, according to the complaint. Officers found a loaded assault-style rifle with a scope, a digital camera and a plastic bag of food left behind.

A suspect, identified on Monday as Ryan Routh, 58, was arrested about 40 minutes later driving north on Interstate 95. When asked if he knew why he had been stopped, Routh "responded in the affirmative," according to the complaint. The license plate on his vehicle had been reported stolen from another car.

Records show a phone associated with Routh was located at the golf course starting at 1:59 am on Sunday morning, 11-1/2 hours before the incident.

Routh has at least two prior felony convictions, both in North Carolina, according to the criminal complaint.

In 2002, Routh pleaded guilty to possession of an unregistered fully automatic gun, defined in North Carolina law as a weapon of mass destruction, according to the county district attorney's office, and was sentenced to probation. He was also convicted of possessing stolen goods in 2010.

Trump's campaign schedule will remain unchanged, according to a source with knowledge of the matter. He is scheduled to unveil a new cryptocurrency business on X on Monday night, and will host a town hall in Michigan on Tuesday and a rally in Wednesday in New York.

Trump blamed President Joe Biden and Vice President Kamala Harris, the Democratic presidential candidate, for the apparent assassination attempt. He claimed the suspected gunman was acting on Democrats' "highly inflammatory language," though authorities have not yet offered evidence of any motive.

"Their rhetoric is causing me to be shot at, when I am the one who is going to save the country, and they are the ones that are destroying the country - both from the inside and out," he said, according to Fox.

On Sunday, Harris said on X: "Violence has no place in America."

Speaking at an event in Philadelphia on Monday, Biden said, "In America, we resolve our differences peacefully at the ballot box, not at the end of a gun."

Local and federal authorities were expected to provide updates at a 4 pm news conference.

Secret service under pressure

The Secret Service, which protects US presidents, presidential candidates and other high-level dignitaries, has been under intense scrutiny since the earlier attempt on Trump's life.

That led to the resignation of Director Kimberly Cheatle. The service bolstered Trump's security detail following the July 13 attack, in which the gunman was shot dead by responding agents.

The agency "needs more help," including possibly more personnel, Biden told reporters on Monday, adding: "Thank God the president's OK."

House of Representatives Speaker Mike Johnson, who convened a bipartisan task force to investigate the first assassination attempt, said in a Fox News interview that Congress would also examine the latest incident.

"We need accountability," said Johnson, who also called for more resources to protect Trump.

Cheatle's replacement, Acting Director Ronald Rowe, traveled to Florida after Sunday's assassination attempt, according to several news outlets. Rowe, who took over after Cheatle's resignation in July, told Congress on July 30 he was "ashamed" of security lapses in the earlier attack.

Rowe has been with the 7,800-member Secret Service for 25 years, according to an official biography, rising to the agency's No 2 spot before he was promoted in July.

Suspect is Ukraine sympathizer

Routh is a staunch supporter of Ukraine and traveled there after Russia's 2022 invasion, seeking to recruit foreign fighters. Ukrainian officials distanced themselves from Routh on Monday, and The International Legion, where many foreign fighters in Ukraine serve, said it had no links with Routh.

Profiles on X, Facebook and LinkedIn with Routh's name contained messages of support for Ukraine as well as statements describing Trump as a threat to US democracy.

"@POTUS Your campaign should be called something like KADAF. Keep America democratic and free. Trumps should be MASA ...make Americans slaves again master. DEMOCRACY is on the ballot and we cannot lose," read a post on X, tagging Biden.

Reuters was not able to confirm that the accounts belonged to the suspect. Public access to the Facebook and X profiles was removed hours after Sunday's incident.

Harris and other Democrats have cast Trump as a danger to US democracy, citing his effort to overturn his defeat in the 2020 election, which led to the Jan. 6, 2021, assault on the US Capitol. Harris has promised unwavering support for Ukraine if elected.

Trump has expressed skepticism about the amount of aid the US has provided Ukraine and has vowed to end the war immediately if elected. He told Reuters last year that Ukraine might have to cede some territory to gain peace.

Elon Musk, the billionaire owner of X, posted and then deleted a message on the social media site on Sunday wondering why no one had tried to assassinate Biden or Harris. In a follow-up post on Monday, Musk, who has endorsed Trump, said he had been joking.