On one side of Pennsylvania Avenue in Washington, D.C., President Trump -- now the only president in history to be impeached twice -- faces another Senate trial following the House charging him Wednesday with one article of impeachment for "incitement of insurrection." Shortly after 10 Republicans sided with Democrats for the vote, Trump released a video from the Oval Office condemning the violence at last week's Capitol riot, which he called a "calamity," but he did not address impeachment.

On the other side of Pennsylvania Avenue stands what's now become a crime scene -- the U.S. Capitol complex. By this weekend, up to 20,000 National Guard troops, many armed, will be deployed to the area amid heightened security concerns and ahead of Biden’s inauguration. Inside the Capitol, metal detectors were installed to enter House chamber earlier this week, and House Speaker Nancy Pelosi announced plans to fine members who don't comply with the new protocol up to $5,000.

Senate Majority Leader Mitch McConnell signaled Wednesday that Trump's Senate trial should take place after Trump leaves office, saying he wouldn't call back the Senate ahead of its Jan. 19 return. McConnell also indicated Wednesday he's considering voting to convict the president, issuing a statement that says he has "not made a final decision." Pelosi has not publicly announced her timeline, but a source involved with deliberations told ABC News Wednesday she plans to send the article to the Senate next week.

Biden, reacting to Trump’s second impeachment late Wednesday, expressed his hope that the Senate will be able to maintain a bifurcated schedule, allowing the trial to move forward along with his agenda -- a message his transition has been consistent on this week. But Democrats are facing the reality that Trump is still likely to loom large over Biden's first days in office.

On Thursday evening, Biden is slated to deliver remarks on the public health and economic crises from Wilmington, Delaware, and introduce his COVID-19 vaccine and economic relief proposal. Vice President-elect Kamala Harris is expected to join.

There are no public events on Trump’s schedule.

With Trump facing a Senate trial as soon as next week, he has no organized defense team as his top lawyers have refused to represent him.

White House counsel Pat Cipollone, his deputies, and outside lawyers Jay Sekulow, and Jane and Marty Raskin are not expected to be involved.

Trump has been increasingly irritated with his personal attorney Rudy Giuliani and hasn’t been taking his calls, according to sources familiar with the matter, though Giuliani has been spotted in the West Wing recently.

And former Harvard professor Alan Dershowitz is not on board yet, though aides to the president have had discussion with him about joining the team.

Another attorney, John Eastman, whose extremist positions have troubled some members of the president’s legal team recently, is expected to take some sort of role in Trump’s impeachment defense.

Eastman represented the president in the Texas dispute and has previously pushed a racist conspiracy theory about Vice President-elect Kamala Harris.

Trump has asked top aides about how a Senate trial would look this time around. As he did during his first impeachment, Trump raised the idea of testifying himself, which aides dissuaded him from pursuing.

-ABC News' Katherine Faulders and John Santucci

Lady Gaga and Jennifer Lopez will lend their voices to Biden's inauguration next week, performing when he officially becomes the 46th president of the United States, Biden's Presidential Inaugural Committee announced Thursday morning.

The announcement detailing participants in the 59th inaugural swearing-in ceremony represents one of the more traditional aspects of Biden's inauguration, which has been largely altered amid the COVID-19 pandemic to accommodate an at-home audience, and facing new concerns over security in the wake of a riot at the Capitol last week that left five dead.

Gaga, who appeared on the campaign trail with Biden during the 2020 election and worked with the then-vice president on his "It's on Us" campaign to combat campus sexual assault, will perform the national anthem when Biden is sworn in, the committee announced.

Lopez, who endorsed Biden, and took part in a virtual chat with the president-elect during the campaign, is also slated to perform at the event.

-ABC News' Molly Nagle

Ten is either a huge number or a stunningly small one, depending on one's views of the state of partisanship and Trump's culpability for his words and actions.

But 10 Republicans won't be enough to bring true consequences to the soon-to-be-former president. That will fall to the Senate, where the focus will be in the early days of the Biden presidency, now that the House voted in the quickest and most bipartisan impeachment in American history.

Senate Majority Leader Mitch McConnell is making clear that impeachment will be Senate Minority Leader Chuck Schumer's to handle, once they trade jobs late next week. McConnell's public statement not to have prejudged the outcome matters greatly at the outset of the coming trial.

All of the dynamics will be different by this time next week. Soon-to-be-President Biden will have appointees to confirm and a COVID-19 relief bill he wants passed; more will emerge about how last Wednesday's indignities came to pass; and the nation will know whether Biden will be allowed to take office peacefully in the end.

Plus, the Senate is just different than the House. There are different personalities and election cycles, different ambitions, more and different potential coalitions and partnerships, and an overall sense of more independence from presidents.

Trump's legacy has been sullied by the events of the past week and a second impeachment leaves its own permanent mark. But final and official judgments will fall to the body Biden knows so well -- and where he is likely to look to build his own presidential legacy starting quite soon.

-ABC News' Political Director Rick Klein

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