US Republican presidential candidate Donald Trump vowed to bring change to a "broken system" in Washington, in a speech today laying out plans for his first 100 days in office if elected president on 8 November.

The billionaire real estate magnate vowed to "drain the swamp in Washington" and replace it "with a new government of, by and for the people" - echoing Abraham Lincoln's famous 1863 Civil War address.

Mr Trump gave his speech in Gettysburg, Pennsylvania, best known as the site of a decisive civil war battle and cemetery, and the place where Republican president Abraham Lincoln delivered a famous address.

"Change has to come from outside our very broken system," Mr Trump told several hundred supporters.

"Our campaign represents the kind of change that only arrives once in a lifetime."

In his 45-minute speech, delivered using prepared remarks instead of in his usual off-the-cuff style, Mr Trump laid out proposals for his first 100 days in office.

Mr Trump pledged to deliver "at least 25 million jobs in one decade," tame illegal immigration, impose congressional term limits, renegotiate the North American Free Trade Agreement (NAFTA) - and repeal US President Barack Obama's signature health care reform.

He also said he would "cancel billions in payments to UN climate change programmes" and use the savings "to fix America's water and environmental infrastructure".

Mr Trump also listed many of his familiar campaign pledges, such as renegotiating or pulling out of trade deals like NAFTA and the Trans-Pacific Partnership (TPP).

"I am not a politician, and have never wanted to be one," Mr Trump said. "But when I saw the trouble our country was in, I felt I had to act."

Meanwhile, Mr Trump has gained ground on his Democratic rival Hillary Clinton, cutting her lead nearly in half, according to Reuters/Ipsos polling.

The polling data found Mr Trump's argument that the 8 November election is "rigged" against him has resonated with members of his party.

"Remember folks, it's a rigged system," Mr Trump told a Pennsylvania rally last night.

"That's why you've got to get out and vote, you've got to watch. Because this system is totally rigged."

Mrs Clinton led Mr Trump 44% to 40%, according to the 14-20 October Reuters/Ipsos poll.

That compared with 44% for Mrs Clinton and 37% for Mr Trump in the 7-13 October poll released last week.

An average of national opinion polls by RealClearPolitics shows Mrs Clinton 6.2 percentage points ahead at 48.1% support to Mr Trump's 41.9%.

However, Mrs Clinton maintained her commanding lead in the race to win the Electoral College and claim the US presidency, according to the latest Reuters/Ipsos States of the Nation project results released today.

In the last week, there has been little movement. Mrs Clinton leads Mr Trump in most of the states that Mr Trump would need should he have a chance to win the minimum 270 votes needed to win.

According to the project, she has a better than 95% chance of winning, if the election was held this week. The mostly likely outcome would be 326 votes for Mrs Clinton to 212 for Mr Trump.

Mr Trump's campaign was thrown into crisis after a 2005 video released this month showed him bragging about groping and kissing women.

He has since faced accusations - which he has said are "absolutely false" - that he made improper sexual advances to women over decades.