WASHINGTON — House Speaker Nancy Pelosi, D-Calif., called on members of Congress to stand up to "lawlessness and tyranny" on Wednesday, as she marked the start of the final formal debate in the House over whether to impeach President Donald Trump.

"For centuries, Americans have fought and died to defend democracy for the people. But, very sadly now, our founders' vision of a republic is under threat from actions from the White House," Pelosi said on the House floor.

"That is why today, as speaker of the House, I solemnly and sadly open the debate on the impeachment of the president of the United States," Pelosi continued. "If we do not act now, we would be derelict in our duty."

The California Democrat said it is "tragic that the president's reckless actions make impeachment necessary" but added, "He gave us no choice."

Pelosi's remarks were the first in what was slated to be at least six hours of formal debate in the House, during which each member of the House would be afforded a minimum of about a minute to address the chamber.

Following this debate, the Democratic-controlled House is expected to approve two separate articles of impeachment, charging Trump with abuse of power and obstruction of Congress. The historic vote is slated to take place sometime Wednesday evening, and the vote breakdown will almost certainly fall along party lines.

"It is a matter of fact that the president is an ongoing threat to our national security and the integrity of our elections, the basis of our democracy," Pelosi continued, addressing more than 100 Democratic members seated on the Democratic side of the House chamber and the handful of Republicans seated across from them.

The speaker also quoted her dear friend, the late Rep. Elijah Cummings, D-Md., who served as chairman of the House Oversight Committee until his sudden death earlier this fall.