Donald Trump has challenged voters to save the American dream in a scathing attack on his rival for the White House, Joe Biden.

On the final night of the Republican convention, and using the White House as a Hollywood-style backdrop, the President told a large and, significantly, largely unmasked audience: "Your vote will decide whether we protect law-abiding Americans, or whether we give free rein to violent anarchists, agitators and criminals who threaten our citizens."

The 74-year-old is currently polling eight points behind the Democratic nominee with just over two months until the country heads to the ballot.

But in a bid to win over more undecided voters, Trump took the opportunity to drill home the difficulties he believes Americans would face with Biden in the Oval Office, drawing on his opponent’s experience as vice-president to Barack Obama.

He said: "This election will decide whether we save the American dream or whether we allow a socialist agenda to demolish our cherished destiny.

Trump and Biden will go head-to-head in the first election debate on September 29.

On Wednesday, Trump bizarrely called for drugs tests to be conducted on him and Biden prior to the debate.