"The President, Vice President and all civil Officers of the United States, shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors."
~Article II, Section 4 of the United States Constitution
~Impeachment Trial of President Andrew Johnson
Presidential Impeachment is a two stage Constitutional process. The full power of Impeachment and the removal of a sitting President resides within Congress. The actual impeachment of a President is the sole power of the House of Representatives. Once a President is impeached, the power of removing the President shifts to the U.S. Senate.
The House of Representatives starts the impeachment process by publicly investigating the charges and holding hearings. If the House of Representatives votes against impeachment the process is over and the President is not Impeached.
If the House of Representatives votes for Impeachment of the President, the process moves forward with the drawing up of the Articles of Impeachment (The official criminal charges for removal from office). The President has now been officially impeached per the United States Constitution. Once the Impeachment process is final, trials are then held in the U.S. Senate to convict or acquit the President of the Articles of Impeachment drawn against him.
In 1867 the 17th U.S. President Andrew Johnson, successor to the Presidency when Abraham Lincoln was assassinated, became the first President in American History to be impeached. Over One Hundred and Thirty years later history would repeat itself.
President Bill Clinton made a public apology from the White House Rose Garden on December 11, 1998 for his "words and deeds" during his presidency which brought the impeachment inquiry of Congress. Bill Clinton was impeached on December 19, 1998. He is the second and only other President in American History to be impeached. In both Presidential impeachments the Articles of impeachment were
drawn and a criminal trial in the U.S. Senate proceeded. However, both Johnson and Clinton were acquitted of the charges and were not removed from office. Johnson was spared removal of the high office by only one Senate vote.
Vice President for just one month, Tyler insisted upon assuming the full powers of a duly elected President setting a new precedent. It wasn't until the 25th amendment to the U.S. Constitution was ratified in 1967 that succession was explicitly written.
Therefore, Congress considered his excessive use of the veto power an abuse of power and in 1843 Tyler would also become the first Presidential impeachment attempt by having an impeachment resolution introduced in the House of Representatives, lead by committee head House Representative John Quincy Adams. However, the full House was not convinced and the attempt failed miserably.
In 1974 the House of Representatives were in talks about the impeachment of Richard M. Nixon in connection to the Watergate scandal and decided to bring it to a vote on three Articles of Impeachment: Obstruction of justice, Misuse of powers and violation of his oath of office, and failure to comply with house subpoenas.
On August 9, Richard Nixon resigned as President before the vote of impeachment could be cast on the House floor which was to be voted on around August 24th. Had Nixon not resigned, it is believed the vote would have gone against him and a criminal trial in the Senate would have followed. Richard Nixon is the only President in American History to resign as a sitting President. Nixon was later pardoned by his successor Gerald R. Ford, exonerating him of any criminal charges.Here for more about the Resignation of Richard Nixon...
AMERICAN PRESIDENTS OATH OF OFFICE
"I do solemnly swear (or affirm) that I will faithfully execute the office of the President of the United States, and will to the best of my ability, preserve, protect, and defend the Constitution of the United States."
~United States Constitution, Article II, Section I, Clause 8