Ms Pelosi said she opened debate "solemnly and sadly", insisting if the House does not act now, "we would be derelict in our duty".
She said Mr Trump used his office to obtain an "improper political benefit" from Ukraine at the expense of the nation's security.
She said the House was forced to add a second article of impeachment against the president, obstruction of Congress, because "never before in the history of our nation have we seen a president declare and act as he is above the law".
After a day of debate, the House will vote on the two articles of impeachment against the Republican president later on Wednesday.
The Republican-controlled Senate is expected to acquit him in a trial next year.
U.S. President Donald Trump's bank account in China raises serious national security concerns, U.S. House of Representatives Speaker Nancy Pelosi said on Wednesday, following a New York Times report revealing the previously undisclosed account. Gavino Garay reports.
The U.S. Supreme Court on Tuesday blocked a lower-court ruling that had ordered the country's decennial population count be continued until Oct. 31. The Census Bureau said on Aug. 3 that it would wind down data collection by Sept. 30, a month earlier than originally scheduled. This report produced by Chris Dignam.
The Democratic-led U.S. House of Representatives passed a stopgap funding bill on Tuesday to keep the federal government operating through Dec. 11, after striking a deal with Republicans on aid for farmers and nutritional assistance to children. Ryan Brooks reports.
U.S. Democratic presidential candidate Joe Biden warned the United Kingdom that it must honour the Northern Irish peace deal as it extracts itself from the European Union or there would be no U.S. trade deal. Adam Reed reports.
[NFA] The U.S. Justice Department said on Monday it has indicted six Russian intelligence agency hackers for a four-year long hacking spree that included attacks against the 2018 PyeongChang Winter Olympics and 2017 French elections. Freddie Joyner has more.
Photo by Mikhail Svetlov/Getty Images The United States accused six Russian government officials of orchestrating a string of high-profile cyberattacks that caused billions of dollars in damage in indictments unsealed on Monday. The alleged cybercrimes include attacks that took down parts of Ukraine's power grid, disrupted the Olympic games in South Korea, and disrupted the computer systems of several US hospitals.
Two aides to former President George W. Bush are putting together their own theories as to why Speaker Nancy Pelosi has yet to send the articles of impeachment to the Senate, and it has to do with the..
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