Washington, June 21 (IANS: Briton who tried to grab a police officer's gun at presumptive Republican nominee Donald Trump's rally in Las Vegas said he wanted to shoot the the billionaire, court papers said.

Michael Steven Sandford, 20, who is charged with an act of violence "on restricted grounds", did not enter a plea when he appeared before a judge in Nevada and was remanded in custody until a hearing on July 5, BBC reported.

Sandford had tried to seize the gun after saying he was seeking Trump's autograph at Saturday's rally.

The man said he was planning and trying to shoot Trump for about a year but had decided to act now because he finally felt confident enough to do so, papers said.

A federal judge found Sandford, who appeared in court in shackles, to be a danger and risk of non-appearance.

When asked about Sandford's arrest, a Foreign Office spokesman said: "We are providing assistance following an arrest of a British national in Las Vegas."

Earlier on Monday, Trump fired his campaign manager Corey Lewandowski who oversaw his triumph in the primary contests.

The US presidential election campaign of 2016 has been fringed with violence. Trump attracts protests almost everywhere he goes.

The tycoon often mocks the demonstrators and there have been clashes with his supporters, both inside and outside of his packed, emotionally charged rallies.

For some, the violence has stirred dark memories of 1968 when Democratic presidential contender Robert Kennedy was assassinated and riots broke out at the party's convention in Chicago.

This year also, the country feels edgy and the Secret Service, which guards candidates as well as presidents, has been on high alert.

Agents swarmed around Trump in Ohio in March after a man apparently attempted to climb on to the stage where he was speaking.

Other events were cancelled because of security concerns. With five months to go, many Americans are worried about where this election is heading.

According to the court papers, Sandford said he had never fired a gun before but went to a range in Las Vegas on June 17 to learn how to shoot.

At Saturday's rally at the Treasure Island Casino, Sandford, who was in the US for a year and half, had tried to grab the weapon because it was in an unlocked position and therefore, the easiest way to get a gun to shoot Trump.

Documents said Sandford acknowledged that he knew he would only be able to fire one or two rounds, and expected to be killed during an attempt on Trump's life.

He told the police if he had not tried to kill Trump at this rally he would have tried again at a rally in Phoenix, for which he had already booked tickets.

Recent opinion polls suggest Trump is trailing his Democrat opponent Hillary Clinton.

There were reports over the weekend that Clinton's campaign was ahead in spending in key swing states.

Trump's former campaign manager said he still supports his candidacy, despite being sacked.

Lewandowski said the billionaire businessman had changed the way American politics was viewed for the better.

Reports in American media say he clashed with the more traditional strategists Trump has hired recently to try and reshape his operation for the November election.

Trump is facing strong resistance from senior members of his own party over his strident tone, hard-line immigration policy and falling poll numbers.

Americans go to the polls on November 8 to elect a president to succeed Democrat Barack Obama, who is stepping down after two terms in office, which have seen the Republicans gain control of both houses of Congress.