President Joe Biden is set to say that threats by some Republican candidates to refuse to accept election results if they lose is a “path to chaos” and will urge voters to reject election deniers.

The White House has released excerpts of a speech President Biden was to deliver on Wednesday night as he tries to help Democrats face down a strong challenge from Republicans and maintain control of the US Congress.

President Biden will say the November 8 elections are the first since the January 6, 2021, attack on the US Capitol by supporters of then-president Donald Trump.

“I wish I could say the assault on our democracy ended that day. But I cannot,” President Biden will say, according to the excerpts.

President Biden will speak at a Democratic National Committee event at Washington’s Union Station near Capitol Hill.

He will urge voters to “think long and hard about the moment we are in”.

“As I stand here today, there are candidates running for every level of office in America: for governor, for Congress, for attorney-general, for secretary of state who won’t commit to accepting the results of the elections they’re in,” he will say.

“That is the path to chaos in America. It’s unprecedented. It’s unlawful. And, it is un-American,” President Biden will say.

The Democratic National Committee said Biden would “address the threat of election deniers and those who seek to undermine faith in voting and democracy; and the stakes for our democracy in next week’s election”.

President Biden believed it was important to speak out “loud and clear” against political violence and those who had said they would not accept the results of the elections, White House press secretary Karine Jean-Pierre told reporters.

“This is an inflection point,” she told a regular White House briefing.

“What the president believes that what he is seeing and what we are hearing from MAGA Republican officials – extreme Republican officials – who say they are not going to accept this election, is a threat to our democracy.”

The speech comes against the backdrop of the US Capitol assault last year and the weekend attack on the husband of House Speaker Nancy Pelosi, a fellow Democrat.

Most midterm forecasts predict Republicans are almost certain to take control of the House, and show the Senate is a toss-up.

Mr Trump’s supporters stormed the Capitol on January 6, 2021, in an attempt to stop the official certification of Biden’s victory in the November 2020 election.

While reviews by dozens of courts, state authorities and members of Mr Trump’s own administration have repudiated his false claims that his election defeat was the result of widespread fraud, he has continued airing them since leaving office.

– AAP