WASHINGTON — President Biden plans to name on the nation on Thursday to recommit itself to a peaceable democracy, warning that it stays in danger a yr after a mob of President Donald J. Trump’s supporters stormed the Capitol to cease Congress from ratifying his election defeat.

In a speech to be delivered on the Capitol marking the anniversary of the assault, Mr. Biden will supply a putting portrait of the fragility of the two-century-old American system, in accordance with advance excerpts launched by the White Home. Fairly than reaffirm the sturdiness of the union, as presidents sometimes do, he’ll emphasize the risks of its collapse.

“At this second we should resolve what sort of nation we’re going to be,” Mr. Biden plans to say, in accordance with the excerpts. “Are we going to be a nation that accepts political violence as a norm? Are we going to be a nation the place we enable partisan election officers to overturn the legally expressed will of the individuals? Are we going to be a nation that lives not by the sunshine of the reality however within the shadow of lies? We can not enable ourselves to be that sort of nation.”

The speech will kick off a day of commemorations that, as an alternative of showcasing American unity, will underscore simply how fractured the nation stays a yr after Mr. Trump’s refusal to just accept defeat on the poll field stirred backers to invade the Capitol, disrupt the counting of the Electoral Faculty votes and ship lawmakers scurrying for security.

Mr. Biden and Democratic leaders plan addresses, discussions and a candlelight vigil whereas Republican leaders largely intend to remain away. Mr. Trump initially deliberate a information convention at his Mar-a-Lago property in Florida to rail in opposition to the investigation into the assault however canceled to the aid of Republicans who thought-about it counterproductive.

The disparate approaches to the day mirror how a lot Jan. 6 has turn into interpreted by means of a political lens. Democrats view the storming of the Capitol as an existential menace to constitutional democracy in contrast to any in trendy instances. Most Republicans would relatively deal with the rest, with some satisfied that it’s getting used as a partisan weapon in opposition to them and others frightened of crossing Mr. Trump, who continues to wield outsize energy throughout the social gathering.

Emotions stay uncooked on Capitol Hill, a spot of post-traumatic stress that has but to completely recuperate from the psychological and political scars of an assault that led to at least seven deaths and a whole bunch of accidents. Greater than the standard acrimony over legislative variations, the legacy of Jan. 6 has exacerbated the poisonous rift between members and employees aides on reverse sides of the aisle.

Whereas Mr. Biden has hesitated to have interaction in a back-and-forth along with his predecessor, aides mentioned he would use his 20-minute speech to extra instantly blame Mr. Trump for encouraging the violence a yr in the past.

“I’d anticipate that President Biden will lay out the importance of what occurred to the Capitol and the singular accountability President Trump has for the chaos and carnage that we noticed,” mentioned Jen Psaki, the White Home press secretary. “And he’ll forcibly push again on the lies unfold by the previous president and try and mislead the American individuals and his personal supporters.”

Nonetheless, Ms. Psaki didn’t say whether or not Mr. Biden would particularly acknowledge him by title. “Individuals will know who he’s referring to,” she mentioned.

Mr. Biden can also be anticipated to the touch on voting rights, though he has a separate speech on the topic scheduled for subsequent week and Ms. Psaki mentioned the Jan. 6 deal with is “extra targeted on the day, what it means in our historical past and the position that some have performed in persevering with to perpetuate the massive lie.”

Senator Chuck Schumer of New York, the Democratic majority chief, has signaled in recent days that he would make a renewed effort to go stalemated voting rights laws, and liberal activists have known as on Mr. Biden to make use of the anniversary to throw his weight behind the trouble.

However Republicans have accused the White Home and Democrats of politicizing the assault to advertise laws meant to learn their very own social gathering. “It’s past distasteful for a few of our colleagues to ham-fistedly invoke the Jan. 6 anniversary to advance these goals,” mentioned Senator Mitch McConnell of Kentucky, the Republican minority chief.

Many if not most Republicans plan to absent themselves from Thursday’s occasions, with a lot of the social gathering’s senators heading to Georgia for the funeral of their former colleague Johnny Isakson.

Whereas Mr. Trump scrapped his information convention, he continued to situation written salvos in opposition to the Home committee investigating the assault as he seeks to reframe the riot because the comprehensible results of anger on the 2020 election, which he falsely claims was stolen.

Undaunted by the violence a yr in the past, Mr. Trump nonetheless makes use of the form of inflammatory rhetoric that prompted Home Democrats and a handful of Republicans to question him for inciting an rebel. In an announcement Wednesday assailing coronavirus vaccine mandates, he mentioned that “MAGA nation ought to stand up” in opposition to such insurance policies. He additionally once more teased that he would run in 2024 by releasing ballot numbers displaying him main different Republican candidates.

Though Republican leaders will stay formally silent, Mr. Trump’s camp shall be represented by Stephen Okay. Bannon, his onetime chief strategist, who will host a podcast that includes two different Trump allies, Representatives Matt Gaetz of Florida and Marjorie Taylor Greene of Georgia.

Safety forces in Washington have been on alert. The Division of Homeland Safety issued an intelligence evaluation to state and native legislation enforcement on Dec. 30 saying that though some radicals might exploit the anniversary “to advertise or presumably commit violence,” the Biden administration lacked proof of “a selected or credible menace.”

Home extremists, nevertheless, continued to amplify false statements in regards to the 2020 election, in accordance with the evaluation, which concluded that “the most probably menace of violence” on Thursday “stems from lone offenders looking for to focus on perceived ideological opponents, political symbols or legislation enforcement.”

Zolan Kanno-Youngs contributed to this report.