It's officially happening.

House Speaker Nancy Pelosi (D-Calif.) announced Tuesday that the House would formally pursue an impeachment inquiry against President Trump. The decision from the impeachment holdout comes after Trump admitted to urging pushing Ukraine to investigate Joe Biden's son Hunter Biden, with Pelosi saying that the House was "moving forward with an official impeachment inquiry."

Pelosi started by lining up several instances where Trump's actions constituted a "violation of the constitution" and how they "undermine our national security and intelligence." The Ukraine conversations, specifically, amount to Trump's "betrayal of his oath of office, betrayal of our national security, and betrayal of the security of our elections," Pelosi continued.

Pelosi's announcement confirms several reports from earlier in the day, in which Democratic lawmakers and aides told several news outlets Pelosi was prepared to back an impeachment inquiry. Since a whistleblower first reportedly indicated and then Trump admitted to pushing Ukraine's government to investigate Hunter Biden as an apparent attempt at smearing his father's 2020 campaign, previously reluctant House Democrats have flipped to back impeaching Trump.

Still, this doesn't indicate what will change about the current impeachment track House Judiciary Chair Jerrold Nadler (D-N.Y.) is on. He is holding what he calls impeachment hearings and is pursuing a so-called impeachment inquiry, but Pelosi had only been reluctant to use those terms before Tuesday. As CNN's Manu Raju explains it, "Pelosi is endorsing is a continuation of existing investigations" under Nadler and five other House committees so they can collect evidence "to recommend articles of impeachment." Kathryn Krawczyk

Greta Thunberg returned to the World Economic Forum a year after famously observing that "our house is on fire" with a familiar warning.

The Swedish climate activist spoke Tuesday at the World Economic Forum in Davos, Switzerland, returning to the event after saying in a 2019 speech there that "our house is on fire." Opening a panel called "How to Save the Planet: Averting a Climate Catastrophe," Thunberg recalled her speech a year ago while advocating for "radical emission cuts at the source, starting today."

"From a sustainability perspective, the right, the left as well as the center have all failed," Thunberg said. "No political ideology or economic structure has been able to tackle the climate and environmental emergency and create a cohesive and sustainable world. Because, in case you haven’t noticed, that world is currently on fire."

Thunberg went on to blast what she referred to as being "worse than silence" from leaders: "empty words and promises which give the impression that sufficient action is being taken." She also asked leaders at the forum "what will you tell your children was the reason to fail and leave them facing the climate chaos you knowingly brought upon them?"

She concluded by echoing her previous warning, saying, "Our house is still on fire. Your inaction is fueling the flames by the hour. We are telling you to act as if you loved your children above all else."

Thunberg spoke after an address from President Trump, who said "we must reject the perennial prophets of doom and their predictions of the apocalypse." Brendan Morrow

Former National Security Adviser John Bolton has said he is willing to testify at President Trump's Senate impeachment trial, and "Trump's legal defense team and Senate GOP allies are quietly gaming out contingency plans" to make sure that doesn't happen, The Washington Post reports.

Under rules proposed by Senate Majority Leader Mitch McConnell (R-Ky.), the Senate won't vote on whether to allow testimony from new witnesses or other new evidence until after House impeachment managers and Trump's team lay out their arguments and senators ask questions, and four Republicans would have to join all 47 Democrats to approve witnesses. If 51 senators allow subpoenaing witnesses, "McConnell is expected to ensure that those individuals are questioned in a closed-door session rather than a public setting," the Post reports, and Bolton's deposition could be moved to "a classified setting because of national security concerns, ensuring that it is not public."

"But that proposal, discussed among some Senate Republicans in recent days, is seen as a final tool against Bolton becoming an explosive figure in the trial," the Post reports. "First, Republicans involved in the discussions said, would come a fierce battle in the courts," with Trump invoking executive privilege to keep Bolton from talking then asking the courts for an injunction if Bolton "refuses to go along with their instructions."

Republicans are also warning Democrats that if they win on Bolton's testimony, Trump's team will subpoena Hunter Biden — though Senate Democrats seem pretty comfortable with that trade, or perhaps calling that bluff. Nobody's sure if Bolton would help or hurt Trump, but Republicans are not eager to find out. At the same time, a CNN-SSRS poll released Monday found that 59 percent of American adults and a 48 percent plurality of Republicans want the Senate trial to include testimony from witnesses not interviewed by the House. Peter Weber

"Three years ago today, this country took on an extraordinary challenge, and that challenge was to answer the question: Can democracy survive the worst person on Earth?" Jimmy Kimmel said on Monday's Kimmel Live, celebrating the third anniversary of President Trump's inauguration. "And so far, the answer is: Barely."

"The moment Donald Trump put his hand on the Bible and swore to protect and defend the Constitution of the United States, that was his first official lie as president," Kimmel said. "And he just kept going from there. According to The Washington Post, since taking office, Trump has racked up more than 16,000 false or misleading claims," including an average of 22 a day in 2019. To put that in perspective, he said, Trump's 16,241 documented falsehoods are "more than 7,000 more lies than there are visible stars in the night sky," or a pancake stack as high as the Empire State Building.

"It's three years of Donald Trump, which is a lot — it's too much, really," Kimmel said. "So much has transpired over the last 1,000-plus days, and tonight we decided to pay tribute to remember the highlights of these three years under our president, Donald Trump." Needless to say, these are not the clips Trump's campaign will use in his re-election ads or convention highlight reel.

The Daily Show also took a look back at Trump's three years in office, but with more of a toddler-in-chief vibe — and a snappier soundtrack. Watch below. Peter Weber

Michael Avenatti, the lawyer most famous for representing porn actress Stormy Daniels in her case against President Trump, was arrested in California last week and transferred over the weekend to New York's federal Manhattan Correctional Center to face charges of extortion and embezzlement, his lawyers told a federal court on Monday. In fact, lawyer Scott Srebnick wrote, Avenatti is being housed, for reasons that are unclear, in the MCC's "Special Housing Unit on the notorious 10-South," the "most secure secure floor in the entire facility," in "a cell reportedly once occupied by El Chapo, on a floor that houses individuals charged with terrorism offenses."

Not only is Avenatti being held in the freezing cell that once housed notorious Mexican drug trafficker and escape artist Joaquin "El Chapo" Guzman, Srebnick said, but he's on 24-hour solitary confinement with a guard and two cameras keeping watch on him from outside his cell 24 hours a day. MCC appears to have learned from the suicide of another recent inmate, Jeffrey Epstein, as Srebnick alludes to in his filing.

Srebnick asked for the court's help in finding out why Avenatti is under such strict lockdown and in getting him moved to regular incarceration amid the general population of MCC, saying the current conditions are hindering Avenatti's participation in his defense case. Peter Weber

In 1998, when the Senate held an impeachment trial of President Bill Clinton, Alan Dershowitz argued that "if you have somebody who completely corrupts the office of president and who abuses trust and who poses great danger to our liberty, you don't need a technical crime" to impeach. Now that he's part of President Trump's defense team, he argues that "without a crime, there can be no impeachment." Anderson Cooper asked Dershowitz about the apparent discrepancy between those views on CNN Monday night.

Dershowitz said he still believes you don't need a "technical crime," just "criminal-like behavior akin to bribery and treason." He said his argument is consistent, and when Cooper pointed out it isn't, he insisted he "wasn't wrong" in 1998, he just has "a more sophisticated basis for my argument now." Cooper wasn't persuaded by Dershowitz's logic and CNN legal analyst Jeffrey Toobin didn't agree with his legal argument that abuse of power and obstruction of Congress aren't impeachable offenses.

"What is clear is that Alan was right in 1998 and he's wrong now," Toobin said. "The idea that you can only impeach a president for criminal or criminal-like behavior is absurd on its face." Dershowitz disagreed and insisted again he hasn't changed his views. "I wasn't wrong, I'm just far more correct now than I was then," he said. "And I think your viewers are entitled to hear my argument without two bullies jumping on everything I say."

Cooper also spoke with Dershowitz's former Harvard Law colleague Lawrence Tribe, who said Dershowitz is clearly wrong and, sadly, appears to be "selling out, I don't think for money but just for attention." He "was a great teacher," Tribe added and "he's perfectly entitled to defend the president, although I don't like that he pretends he's defending the Constitution instead of the president. He's not the Constitution's client."

On MSNBC, former federal prosecutor Maya Wiley agreed that Dershowitz is dangerously "wrong" while anti-Trump conservative Rick Wilson compared Dershowitz to "a prank character on a reality TV show" spouting "performative B.S." on cable news to make his client happy. Watch below. Peter Weber

Over the weekend, House impeachment managers laid out their case that President Trump was "the Framers' worst nightmare" and should be removed from office for abuse of power and obstruction of Congress, Stephen Colbert said on Monday's Late Show. "In response, the president's lawyers say that abuse of power is not impeachable. Yes it is! It's the most powerful job in the world! That's why abuse of power is the thing a president is not supposed to do."

"With his presidency on the line, Trump is turning to his favorite legal scholar: television," Colbert said. Among the TV lawyers Trump hired is Alan Dershowitz, whose list of past clients is ... notable. Colbert turned on his Trump voice: "Get me Dershowitz! I'm exactly as innocent as Jeffrey Epstein and O.J. Simpson — but Jared, just in case, gas up the Bronco." Dershowitz is going on TV arguing Trump's technically-it-wasn't-a-crime impeachment defense, and Colbert played his exact opposite argument in Bill Clinton's impeachment, plus a doozy of a Dershowtiz quote from Richard Nixon's impeachment.

Trump's "all-star defense team" does include Dershowitz, who's past clients also include Claus von Bülow and Harvey Weinstein, "so he definitely has a type," Jimmy Kimmel deadpanned at Kimmel Live. But "Trump summoned all the ghosts of impeachments past, including Kenneth Starr, who led the case against Clinton and was attacked for it by a number of high-profile people," including Trump.

"Rudy Giuliani will not be on the Trump legal team, but he claims he wants to testify," though "Senate Republicans don't want any witnesses, and they're limiting press access," Kimmel said. "These guys really are something: They don't want witnesses, they don't want new evidence, they don't want reporting, and they don't want people watching — it's almost like they have something to hide. But what could that be? The phone call was 'perfect.'"

Trump is "desperately trying to soothe his ego and pretend he doesn't know the key players in the scandal," but he "knows that ultimately, in the eyes of history, it won't matter whether Republicans successfully rig his impeachment trial to let him off the hook," Late Night's Seth Meyers argued. "No matter what, he will be only the third president in history to face such a trial, and it follows him forever, especially as more damning evidence emerges." Watch below. Peter Weber