“[The Vice Presidency] is the most insignificant office that ever the invention of man contrived or his imagination conceived.”—John Adams
Its powerlessness was a staple of Washington humor: everyone in the capital, it seemed, knew the joke about the unfortunate mother who had two sons who were never heard from again: one was lost at sea, and the other became Vice President.
There is one good thing about this apparently insignificant public official: “Power is where the power goes”. It’s only a “heartbeat” away from the Presidency. If something happens to number One, then number Two leaps to become number One.
The Constitution of the United States says that the Vice President shall preside over the Senate, “but shall have no vote, unless they be equally divided.” It says that in case of the President’s “death, resignation or inability to discharge the powers and duties of said office, the same shall devolve on the Vice-President.”
With the exception of his ability to cast a vote to break a tie in the Senate, the document that created the office attached to it, not a single specific power.
LBJ was fully aware of this political fact when he accepted the nomination to become the running mate of JFK. Fate made the equation work and he indeed became the 36th President of the United States. Since he was a kid at school, he continuously boasted that someday he would become the President of the United States, and through a trick of Destiny, he did.
Source: “The Years of Lyndon Johnson: The Passage of Power” authored by Robert A. Caro