US President Joe Biden will tell Americans his predecessor Donald Trump carries “singular responsibility” for the deadly January 6 attack on the Capitol when he marks the first anniversary of the assault.

The Democrat president and his deputy, Kamala Harris, will speak on Thursday morning at the US Capitol, a year to the day after a mob loyal to Mr Trump raided the complex in a failed attempt to stop the certification of electoral college votes that officially delivered Mr Biden’s election victory.

Since taking office last January, Mr Biden and his top aides have been reluctant to talk directly about Mr Trump, even as the Republican former president continued to spread lies about his election loss.

Democrats, historians and civil rights activists are growing increasingly concerned about the future of the nearly 250-year-old representative democracy.

Thursday’s speech comes after Biden spent months encouraging Americans to unite against the COVID-19 pandemic and rebuild together after weather disasters.

White House Press Secretary Jen Psaki said Mr Biden will “lay out the significance of what happened in the Capitol and the singular responsibility President Trump has for the chaos and carnage that we saw”.

“He will forcibly push back on the lies spread by the former president in an attempt to mislead the American people and his own supporters as well as distract from his role in what happened,” she said.

Mr Trump on Tuesday cancelled a news conference at his Mar-a-Lago estate in Florida that had been scheduled for the evening of January 6, blaming what he called the “bias and dishonesty” of the House of Representatives probe of the attacks and the news media, a favourite target.

Taylor Budowich, a Trump spokesman, said it was “unsurprising” Mr Biden would spend January 6 “trying to further divide our nation”.

“Division is the only thing Democrats know how to do,” he said.

Four people died on the day of the riot, and one Capitol police officer died the day after defending Congress.

Dozens of police were injured during the multi-hour onslaught by Trump supporters, and four officers have since taken their own lives.

The White House said Mr Biden would push back against Mr Trump’s false claims, adopted by many of his followers, that his election defeat was the result of widespread fraud, and attempts to downplay the worst assault on the Capitol since the War of 1812.

Mr Biden has been “clear eyed about the threat the former president represents to our democracy”, Ms Psaki said, “and how the former president constantly works to undermine basic American values and rule of law”.

She added the president sees the deadly attacks as a “tragic culmination of what those four years under President Trump did to our country”.

– AAP