In his first address as president, Biden called for unity, truth and racial justice as the nation faces a worsening pandemic and bitter partisanship.

House Speaker Nancy Pelosi opened her first weekly presser since Democrats took control of the Senate and the White House by praising Biden's message of unity and remaining tight-tipped about when she'll send the article of impeachment charging former President Donald Trump with "incitement of insurrection" to the Senate.

She said the chambers are "ready" to proceed and said "it will be soon" but that transmission of the article is being held up by questions about how the trial will work.

Asked whether the trial could alienate Republican supporters of the president, Pelosi argued that to not hold Trump accountable would be "harmful to unity."

"I don't think it is very unifying to say, 'Oh, let's just forget it and move on.' That is not how you unify. Joe Biden said it beautifully. If you're going to unite, you must remember," Pelosi said.

"Just because he's now gone -- thank God -- you don't say to a president, 'Do whatever you want in the last months of your administration. You're going to get a get-out-of-jail card free,' because people think we should make nice and forget that people died here on Jan. 6," she said.

Pelosi didn't rule out the the possibility that theconduct of lawmakers could come under investigation in a probe of the Capitol Hill riot, accusing some members of giving "aid and comfort" to rioters.

-ABC News' Benjamin Siegel

Biden and Harris, alongside their spouses and five family members, began the day in the White House State Dining Room with a virtual inaugural prayer service broadcast from the Washington National Cathedral.

Four large television screens were set up showing the prayer while the group bowed their heads. Patti LaBelle then sang the “The Star-Spangled Banner” and everyone rose to their feet and put their hands over their hearts.

Biden, a devout Catholic and only the second Catholic president, is not shy about invoking his faith. In his first act as president after taking the oath of office Wednesday, he asked the nation to join together in silent prayer.

-ABC News' Ben Gittleson

Biden's first full day in office is focused on the coronavirus pandemic, with the president set to deliver afternoon remarks and take 10 executive actions aimed to help get the pandemic under control.

Those actions include eight executive orders to trigger the the Defense Production Act to manufacture COVID-19 supplies, require masks in airports and on interstate transportation, require international travelers to the U.S. receive a negative COVID-19 test before arrival, establish a testing board, develop more treatments and vaccines, work to overcome the disproportionate impact of COVID-19 on minority communities, provide guidelines to reopen schools -- as well as a presidential memorandum to reimburse schools for supplies from FEMA funds -- create guidelines to protect workers from exposure, and increase collection and analysis.

His two other actions expected Thursday are a presidential memorandum directing FEMA to increase state reimbursements from 75% to 100% for National Guard personnel and supply costs and a presidential directive to support the international COVID-19 response, which the Biden team is calling an effort to restore America’s leadership on the world stage.

-ABC News' Molly Nagle and Justin Gomez