A 20-year-old British man accused of trying to assassinate Donald Trump at a June rally in Las Vegas has pleaded guilty to the lesser charges of being an alien in possession of a firearm and disrupting an official function.

Michael Sandford, from Dorking in Surrey, was expected to stand trial in October and faced up to 20 years in a US prison, but after signing a plea deal with prosecutors he is likely to be jailed for no more than 27 months. A sentencing hearing will be held at a later date.

Following his arrest during a Trump rally at the Treasure Island casino on 18 June, Mr Sandford told police he had driven from California to kill the Republican presidential candidate. He had tried to grab a policeman’s gun to attack Mr Trump, but he did not get hold of the weapon and no shots were fired in the incident.

On Tuesday Sandford appeared at the US District Court in Las Vegas, where he told the judge: “I tried to take a gun from a policeman to shoot someone and I'm pleading guilty.”

His mother, Lynne Sandford, has said her son suffers from autism and depression and that he would not have understood the consequences of his actions. Ms Sandford told ITV News this week that she had pressed her son to sign the plea agreement. “I was very relieved that he signed it,” she said. “It was a bit of a battle because he is quite headstrong.”

The family now hopes Sandford will be repatriated to the UK for his sentence, so that he can receive treatment close to home. His lawyer Saimo Chahal said a psychiatrist had determined that Sandford was delusional at the time of the incident.