The Vice President of the United States. If that position is vacant, the next in line is the Speaker of the House of Represenatives.
If the president were to resign he would be replaced by the vice president.
When a Senator resigns and there is no pending election at the time, the Governor of the state picks a replacement
who replaces the president of the US senate in his absences
A special election can be held or the governor can appoint someone to the office. They serve what is left of the term.
That would be the Speaker of the House, as long as the Speaker meets the presdential requirements.
The Speaker of the US House of Representatives It is unknown.
VP
The Vice President.
The vice president
If the president dies or resigns, the vice president takes over his job for the remaining years/job.
The vice president
the vice president.
vice-president