A formal accusation of wrongdoing against a public official.
According to the United States Constitution, the House of
Representatives can vote to impeach an official, but the Senate
actually tries the case. Several presidencies have been
blemished by impeachment or the threat of impeachment: President
Andrew Johnson was impeached after the Civil War but was
acquitted. President Richard Nixon resigned from office as the
House of Representatives prepared to initiate impeachment
proceedings. President William Jefferson Clinton was impeached
in 1998 but was acquitted by the Senate the following year.