Wikipedia
A president pro tempore or speaker pro tempore is a constitutionally recognized officer of a legislative body who presides over the chamber in the absence of the normal presiding officer. The phrase " pro tempore" is Latin "for the time being".
In Argentina, a similar role is carried by the Provisional President of the Argentine Senate in the absence of the Vice President of Argentina who is designated, by the 1994 amendment to the 1853 Constitution, as the Senate President.
Usage examples of "president pro tempore".
Although Dilman, as President pro tempore of the Senate, had been wielding the gavel since the Vice-President’.
He was simply greeted by the president pro tempore of the Senate, John Langdon of New Hampshire, and conducted to his chair at the head of the chamber.
Atchison was president pro tempore of the Senate then, and under the law in force at the time the succession would have devolved upon him, but he wasn't sworn in, he didn't do anything presidential (I believe he took a nap), and nobody to this day is really sure if he was president or not.
He turned to shake the hand of the Speaker of the House, the President Pro Tempore of the Senate, and his own Vice President, Roger Durling.
Under the Twenty-fifth Amendment, the Vice President and a majority of the Cabinet may together, in writing, communicate to the President pro tempore of the Senate and the Speaker of the House of Representatives their view that the President is no longer able to discharge the powers and duties of his office.
Byrd, the 83-year-old West Virginia Democrat president pro tempore of the SenÂ.
Plus the Speaker of the House, president pro tempore of the Senate, Secretary of State, and so on.
The president pro tempore, Carl Hayden of Arizona, had been in Congress since his state entered the Union in 1912 and in the Senate for forty years.
No new Speaker, no new President pro tempore of the Senate is to be elected to take precedence over you.
The Speaker of the House, John Lipton, and the president pro tempore of the Senate, Jerry Bookout, were progressives and strong supporters of mine.