Biden and Vice President-elect Kamala Harris have announced additional White House picks -- with many familiar faces from Biden's 2020 campaign staff.

While she was not expected to join the administration and instead return to her communication’s firm SKDKnickerbocker, Anita Dunn will be serving as a senior adviser to the president -- marking yet another longtime Biden adviser and a member of the highest echelons of his campaign joining the White House in a senior role.

TJ Ducklo, the national spokesperson for the campaign, will also join the White House as deputy press secretary alongside Karine Jean-Pierre. Deputy press secretary Matt Hill will join as a senior associate communications director.

Biden’s campaign photographer and videographer will also take on similar roles in the administration.

-ABC News' Molly Nagle

The House of Representatives' Committee on Oversight and Reform has sent letters to two dozen hotels and private travel companies seeking help in identifying rioters and preventing future attacks in Washington, D.C., ahead of Biden's inauguration.

"While the inciters and attackers bear direct responsibility for the siege on the Capitol and will be held fully accountable, they relied on a range of companies and services to get them there and house them once they arrived—companies that law-abiding Americans use every day, but whose services were hijacked to further the January 6 attacks," committee chairwoman Rep. Carolyn Maloney, D-N.Y., wrote in the letters. "Trump supporters chartered scores of buses and vans and drove in caravans to the nation’s capital. They stayed in D.C. hotels, with videos showing attackers relaxing in the lobby of one hotel after the insurrection."

The committee has asked the businesses -- ranging from major hotel chains to bus and car rental companies -- to retain records of January reservations for future congressional investigations, to put in place additional screening measures "to ensure that your services are not being used to facilitate violence or domestic terrorism," and to provide information to the committee by Jan. 29 on those measures.

-ABC News' Ben Siegel

The danger to the public and to law enforcement officers from explosive devices during expected upcoming protests "is substantial," the Federal Bureau of Investigation warned in a new awareness bulletin obtained by ABC News on Friday.

The document is full of photos of devices used in the last eight months against civilian and law enforcement targets during public demonstrations.

"Devices targeting infrastructure also increased following violent activity during this time period," the bulletin states.

The FBI now wants to make first responders aware of what has been deployed in the past and what they might encounter during protests linked to the presidential inauguration on Jan. 20.

"The danger posed to law enforcement officers and the general public from the all the tactics listed is substantial," the bulletin states. "If a suspicious item is reasonably believed to contain explosives, an IED, or other hazardous material, DO NOT touch, tamper with, or move the item. Only bomb disposal personal should handle any suspected devices that are located."

An internal FBI bulletin obtained by ABC News earlier this week stated that armed protests are being planned at all 50 state capitols as well as at the U.S. Capitol in Washington, least through Inauguration Day.

The warning comes after suspected pipe bombs were found last week outside both the Democratic National Committee and the Republican National Committee headquarters, just a few blocks from the Capitol where pro-Trump rioters stormed the building.

-ABC News' Aaron Katersky

Biden has chosen Dr. David Kessler, former commissioner of the Food and Drug Administration (FDA), to help lead the federal government's COVID-19 vaccine initiative.

Kessler, a pediatrician and lawyer who headed the FDA from 1999 to 1997 under the Bush and Clinton administrations, will replace Dr. Moncef Slaoui, who is the current chief science officer to Operation Warp Speed.

Biden also announced several other appointees who will join his incoming administration's COVID-19 response team.

"We are in a race against time, and we need a comprehensive strategy to quickly contain this virus," the president-elect said in a statement Thursday. "The individuals announced today will bolster the White House’s COVID-19 Response team and play important roles in carrying out our rescue plan and vaccination program. At a time when American families are facing numerous challenges I know these public servants will do all that is needed to build our nation back better."

House Leader Steny Hoyer, D-Md., began by stressing that Trump's action's last week "demand urgent, clear action by the Congress," and praised House Republican Conference Chair Liz Cheney and a handful of Republicans for agreeing with Democrats that Trump ought to be impeached.

"This is the daughter of the former Republican whip and former vice president of the United States of America. She knows of what she speaks, and she said this as well, 'There has never been a greater betrayal by a president of the United States of his office and his oath of Constitution," he said. "This is not, as Liz Cheney said, just some action. She characterized it as the biggest betrayal of any president of the United States in our history."

Hoyer went on to list GOP Rep. John Katko of New York, the ranking Republican on the Homeland Security Committee who Hoyer described as "not some back-bencher on your side of the aisle" and Rep. Adam Kinzinger of Illinois, among the five House Republicans who have publicly stated they'll vote to impeach the president.

"Mr. Kinzinger said this," Hoyer said, "If these actions are not worthy of impeachment, then what is an impeachable offense? There is no doubt in my mind that the president of the United States broke his oath and incited this insurrection."

Hoyer said other Republicans who he has talked to "in the past 24 hours" agree the president's actions are impeachable.