Following his brief speech, Biden, first lady Jill Biden, Vice President Kamala Harris and second gentleman Doug Emhoff walked out to the South Portico at the White House where candles were lit and displayed on the steps for the moment of silence.

Earlier, the National Cathedral rang its bells to honor the more than 500,000 Americans who died from the coronavirus.

"I received a letter from a daughter whose father died of COVID-19 on Easter Sunday last year," Biden said before the ceremony. "She and her children, his grandchildren, enter Lent this season, a season of reflection and renewal, with heavy hearts. Unable to properly mourn, she asked me in the letter, what was our loss among so many others? Well, that's what has been so cruel."

"So many of the rituals that help us cope, that help us honor those we loved, haven't been available to us. The final rites, with family gathered around, the proper home going, showered with stories and love, tribal leaders passing out the final traditions of sacred cultures on sacred lands," he continued. "As a nation, we cannot and we must not let this go on. That's why the day before my inauguration ... I said, 'to heal -- to heal, we must remember.' I know it's hard. I promise you, I know it's hard. I remember. But that's how you heal. You have to remember."

In remarks ahead of a candlelight ceremony, Biden addressed the nation.

"Today we mark a truly grim, heartbreaking milestone: 500,071 dead," Biden said.

"That's more lives lost to this virus than any other nation on Earth. But as we acknowledge the scale of this mass death in America, remember each person and the life they lived," he continued.

"We often hear of people described as 'ordinary Americans.' There's no such thing. There's nothing ordinary about them. The people we lost were extraordinary. They spanned generations. Born in America, immigrated to America, but just like that, so many of them took their final breath alone in America," Biden said. "As a nation, we can't accept such a cruel fate. While we've been fighting this pandemic for so long, we have to resist becoming numb to the sorrow. We have to resist viewing each life as a statistic or a blur or on the news. We must do so to honor the dead, but equally important, care for the living, those they left behind -- for the loved ones left behind."

The House is one step closer to sending the White House's $1.9 trillion COVID-19 relief package to the Senate after the bill advanced through the House Budget Committee Monday. The committee favorably reported the proposal to the full House in a near-party line 19-16 vote.

"We are in a race against time," House Budget Committee Chairman John Yarmuth, D-Ky., said. "Aggressive, bold action is needed before our nation is more deeply and permanently scarred by the human and economic costs of inaction."

Republicans decried the price tag for the package and accused Democrats of using the pandemic as an excuse to pass key agenda items, including the $15 an hour minimum wage increase.

-ABC News' Benjamin Siegel

The president issued a proclamation following the U.S. recording 500,000 deaths from COVID-19 and he noted that this means more Americans have now died from the virus in one year, compared to in World War I, World War II and the Vietnam War combined.

At 6 p.m., Biden will deliver remarks on the more than 500,000 lives lost to COVID-19 and then he, Harris and their spouses will observe a moment of silence and hold a candle-lighting ceremony at sundown.

In addition, Biden ordered flags lowered to half-staff on federal property for the next five days.

Earlier Monday, White House press secretary Jen Psaki told ABC New Chief White House Correspondent Cecilia Vega that the administration is still working to undo the "inherited" circumstances of the pandemic, taking a swipe at the Trump administration.

"Our focus is on building out of the hole that we inherited," Psaki said.

-ABC News' Sarah Kolinovsky and Justin Gomez

Garland described the Jan. 6 insurrection at the Capitol as "the most heinous attack on the democratic processes I have ever seen and one I never expected to see in my lifetime." He added he will make sure to provide career prosecutors all the resources they need to carry out their investigations while also taking a broader look at the symptoms behind the country's domestic extremism problem.

Asked by Sen. Dianne Feinstein, D-Calif., whether the president "has the absolute right to do what he wants with the Justice Department," Garland said presidents are "constrained by the Constitution as are all government officials" and cited comments by Biden committing to not interfere with Justice Department matters. At the same time, Garland said that the Department of Justice is part of the executive branch and because of that, on policy matters they do "follow the lead of the president and the administration as long as it is consistent with the law." When asked who an attorney general represents when his interests conflict with the president's, Garland said the attorney general "represents the public interest, particularly and specifically as defined by the Constitution and the statutes of the United States."

Asked whether the president can order an attorney general to open or close an investigation, Garland said such a question was a hard one for constitutional law but that he did not expect it to be a question for himself given President Biden's statements assuring independence for the department.

Sen. Lindsey Graham, R-S.C., took a contentious tone with Garland in his line of questioning as he pressed him on multiple topics. At one point, when Graham asked Garland whether he thought former FBI Director Comey was a good FBI director, Garland declined to answer, which Graham said he found "stunning" because he thought Comey was terrible. Sen. Sheldon Whitehouse, D-R.I., pressed Garland on whether he would commit to investigating not only the rioters who attacked the Capitol on Jan. 6, but those "upstream" like the funders, organizers, ringleaders or others not actually at the Capitol.  Garland cited his past experience as a line prosecutor, noting "we begin with the people on the ground and we work our way up to those who are involved and further involved -- and we will pursue these leads wherever they take us."

Asked about whether he would end the Trump Justice Department's policy of generally stonewalling in the face of oversight requests from Congress, Garland committed to Whitehouse that the department would be "as responsive as possible" to any requests and "at the very least why if it can't answer a question or can't answer a letter." Garland also committed that he would work with Whitehouse on getting answers to the committee on requests that the Justice Department under Attorneys General Bill Barr and Jeff Sessions previously ignored.

In an exchange with Sen. John Cornyn, R-Texas, Garland committed that his personal politics will have no impact on prosecutions and investigations he oversees as attorney general. Asked what he would do if he was ordered to do something that he considered to be unlawful, Garland said he would first tell the president or whoever else was asking him that what they were ordering was unlawful and would resign if no alternative was accepted.

Asked by Sen. Amy Klobuchar, D-Minn., what he will do to improve morale in the department, Garland said he would on his first day make an oath to career prosecutors and agents "that my job is to protect them from partisan or other improper motives." Klobuchar then asked Garland whether he believes he'd need "additional authorities" to combat the country's domestic terrorism problem. Garland said while the department "is probably always looking for new tools ... the first thing we have to do is figure out whether the tools that we have are sufficient."

-ABC News' Alexander Mallin