The Senate Commerce, Science and Transportation Committee is expected to hold Pete Buttigieg's nomination hearing for transportation secretary on Thursday at 10 a.m.

This is the sixth Cabinet-level nomination hearing to be noticed. Others expected for next week: Avril Haines to serve as director of national intelligence, Janet Yellen to serve as treasury secretary, Tony Blinken to serve as secretary of state, Lloyd Austin to serve as secretary of defense, and Alejandro Mayorkas to serve as Department of Homeland Security secretary.

The nomination hearing for Avril Haines, Biden’s pick for director of national intelligence, is now scheduled for Tuesday, the Senate Intelligence Committee announced. The hearing is slated to start at 10 a.m. ET.

It was originally scheduled for Friday but was then postponed.

A spokesperson for the U.S. Army confirmed that there will be 25,000 National Guardsmen in the nation’s capital to aid with security for Biden’s inauguration.

“The Defense Department has agreed to provide up to 25,000 service members to support the Presidential Inauguration National Special Security Event federal law enforcement mission and security preparations, as led by the U.S. Secret Service,” the spokesperson said. “The Department of the Army and the National Guard Bureau are working on a sourcing solution now to support this request.”

-ABC News’ Luis Martinez

The FBI, DHS, Secret Service and U.S. Capitol Police, along with several local law enforcement agencies, have issued an extensive "threat assessment" surrounding Wednesday's inauguration.

It covers a range of threats surrounding the inauguration, including not only physical threats from domestic terrorists but also influence campaigns from Russia, China and Iran stemming from the Capitol siege. It even covers physical threats from drones.

The memo says domestic extremists is the “most likely” threat to the inauguration, citing recent incidents of ideologically motivated violence, including the deadly mob at the U.S. Capitol building.

Regarding foreign concerns, the assessment said that since the incident at the Capitol, “Russian, Iranian, and Chinese influence actors have seized the opportunity to amplify narratives in furtherance of their policy interest amid the presidential transition.”

“We have not identified any specific, credible information indicating that these actors intend to explicitly commit violence,” it added. “Furthermore, we have not identified any specific, credible cyber threat to critical infrastructure supporting the upcoming Presidential Inauguration nor a specific credible cyber threat to military or law enforcement personnel supporting the event."

The memo did say, however, that Russian state media has “amplified themes related to the violent and chaotic nature of the Capitol Hill incident, impeachment of President Trump, and social media censorship.”

Iranian state media has “continued to stoke claims that President Trump encouraged and incited the violence, as well as calls to invoke the 25th amendment,” the memo added. It has also “amplified perceived concerns related to President Trump’s mental health and the prospect of other risky actions he could take before leaving office.”

Finally, it noted that Chinese media has “seized the story to denigrate US democratic governance -- casting the United States as broadly in decline -- and to justify China’s crackdown on protestors in Hong Kong."

Lastly, the memo warned that drones could disrupt law enforcement operations at the inauguration, though it added that it does not have “specific, credible information” indicating malicious actors have plans to use unmanned aircraft systems to target the event.

-ABC News’ Mike Levine

House Democrats have opened an investigation into what law enforcement and the intelligence community knew about threats to the Capitol ahead of the Jan. 6 siege.

The investigation from the House Intelligence, Oversight, Homeland Security and Judiciary committees will also examine whether anyone with security clearances -- current or former National Security, Defense, Justice or Homeland Security officials -- participated in the riot.

The investigation will also examine the federal law enforcement response in the aftermath of the attack.

"The Committees will conduct robust oversight to understand what warning signs may have been missed, determine whether there were systemic failures, and consider how to best address countering domestic violent extremism, including remedying any gaps in legislation or policy," committee members wrote in a letter to the FBI, DHS and Office of the Director of National Intelligence.

"This still-emerging story is one of astounding bravery by some U.S. Capitol Police and other officers; of staggering treachery by violent criminals; and of apparent and high-level failures -- in particular, with respect to intelligence and security preparedness," the letter later stated.

Democrats plan to request documents and briefings from administration officials as part of the investigation -- just one of several looking into the Capitol attack.

-ABC News' Benjamin Siegel