The impeachment trial of President Donald Trump (R) began on Thursday when seven House impeachment managers, led by Rep. Adam Schiff (D-Calif.), presented to the U.S. Senate two articles of impeachment against Trump for abuse of power and obstruction of Congress.

Supreme Court Chief Justice John Roberts was sworn in as the presiding officer of the trial. Ninety-nine U.S. senators—Sen. James Inhofe (R-Okla.) was not present—were then sworn in by Roberts to serve as jurors.

The trial is expected to continue with opening statements on Jan. 21.

Trump is the third president in U.S. history to be impeached. President Andrew Johnson was acquitted in 1868 after being charged with violating the Tenure of Office Act. In 1999, President Bill Clinton was acquitted of two charges for perjury and obstruction of justice.

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