I think the president becomes official at NOON the day of inauguration, whether he takes the oath or not.
The same one that the senate, president, and justices take.
Jimmy Carter was the last President to be inaugurated on the east side of the Capitol on January 20, 1977.
John Tyler
He took the oath of office on March 14, 1861 for the first time administered by then Supreme Court Chief Justice Robert B. Taney who was Chief Justice from March 28, 1836 till October 12, 1864.
If the US president dies, the vice-president becomes president and a new vice-president is appointed.If the 'new' president dies, the 'new' vice-president becomes president.This process is dealt with under the 25th Amendment to the US constitution which starts off....Section 1. In case of the removal of the President from office or of his death or resignation, the Vice President shall become President. Section 2. Whenever there is a vacancy in the office of the Vice President, the President shall nominate a Vice President who shall take office upon confirmation by a majority vote of both Houses of Congress.
The constitution requires that before a President can assume their duties they have to take the oath of office. The oath is administered at the official ceremony, the inauguration. When the incoming President speaks the final words of the oath, their Presidency begins and the former President's term in office is officially over.
Oath of Office
All US presidents take the oath of office, starting with the first president, George Washington.
James MonroeThe first president to take the oath was George Washington.
President Obama swore the oath of office on Abraham Lincoln's Bible.
Yes- the President must take the oath of office as required by the US Constitution.
Joe Biden would serve as the President and therefore take the oath of office in the case the Obama did not.
April
First he has to be legally elected as President or else become president by succession. Second he must be "sworn in" by taking the oath of office before a person who is legally qualified to administer oaths.
because it is a tradition and custom
Lyndon Johnson
at noon