“He must go,” the speaker said of a president she has accused of inciting an “armed rebellion against our common country."
“He is a clear and present danger to the nation that we all love,” Ms Pelosi said.
The speaker began her speech in favour of Wednesday’s House impeachment resolution by invoking the words of President Abraham Lincoln as well as a passage from the Bible. She later quoted a prepared speech that former President John F Kennedy was to deliver in November 1963 before he was assassinated.
“Fellow citizens,” Ms Pelosi said, quoting Lincoln’s 1862 State of the Union address, “we cannot escape history. We will be remembered in spite of ourselves. No personal significance or insignificance can spare one or another of us. The fiery trial through which we pass will light us down, in honour or dishonour, to the latest generation.”
Members of Congress “hold the power and bear the responsibility” to condemn Mr Trump for his actions inciting last week’s riot, the speaker said.
Ms Pelosi’s speech kicked off two hours of debate on the impeachment resolution on the House floor on Wednesday, which officially accuses Mr Trump of “incitement to insurrection.”
A small handful of Republicans, including House GOP Conference Chairwoman Liz Cheney, have announced they plan to vote for it later on Wednesday afternoon.
Mr Trump’s first impeachment in December 2019 for upending US national security policy in Ukraine in an attempt to smear Joe Biden did not garner any bipartisan support.
Ms Pelosi urged more Republicans to join Ms Cheney and her small cohort of GOP dissenters, arguing that the president must be impeached and convicted in the Senate to “ensure that the republic will be safe from this man who was so resolutely determined to tear down the things that we hold here and that hold us together.”
The speaker also decried the violent pro-Trump rioters and his attempts last Wednesday to cast them in a positive light: “Those insurrectionists were not patriots. They were not part of a political base to be catered to and managed. They were domestic terrorists. And justice must prevail.”
Mr Trump has since denounced the violence at the Capitol last week, although at the time he told the rioters he “loves” them.
Five people have died as a direct result of last week’s riot, including a US Capitol Police officer bludgeoned to death by the mob and a woman who was shot by a policeman just outside the House chamber.
That death toll doesn’t include at least two other people who have reportedly died by suicide since the mayhem on 6 January: a USCP officer who had been protecting the Senate during the insurrection and a pro-Trump rioter who was subsequently arrested — and then released — in Georgia.
Led by Vice President Mike Pence, Congress was in the middle of certifying Mr Biden’s electoral victory when the pro-Trump throngs breached security at the Capitol and ran roughshod through the legislature, forcing lawmakers to halt the proceedings and scramble for their lives.
The impeachment article, and Ms Pelosi on Wednesday, have framed Mr Trump’s speech to his supporters shortly before they marched to the Capitol — along with his subsequent actions during the riot — as a ham-handed coup attempt.
The Democratic staff of the House Judiciary Committee has compiled 76 pages of materials and evidence to support the prosecution of their case before the Senate.
That evidentiary report concludes that Mr Trump “committed a high Crime and Misdemeanor against the Nation by inciting an insurrection at the Capitol in an attempt to overturn the results of the 2020 Presidential Election.”