Since the poll of the week is about VPs who became Presidents, I thought I would focus on the first one: John Tyler. Unlike today where we assume that if the President dies, the VP takes his place that was not so in Tyler’s time:
Harrison's demise after only a month in office presented the nation with a potential constitutional crisis. The Constitution of that time contained no Twenty-fifth Amendment to lay out procedures governing the vice president's actions when the chief executive became disabled or when there was a vacancy before the end of the incumbent's term. The document provided only that the "Powers and Duties of the said Office . . . shall devolve on the Vice President . . . [who] shall act accordingly, until the Disability be removed, or a President shall be elected." In another section, the Constitution referred to the vice president "when he shall exercise [emphasis added] the Office of President of the United States."
These provisions had occasioned a theoretical discussion between those who believed a person does not have to become president to exercise presidential powers and others who held that the vice president becomes president for the balance of the term.
Tyler’s assumption of the Presidency set the precedent we still follow today:
As the first vice president to succeed to the presidency upon the death of his predecessor, Tyler was determined to transform theory into practice on behalf of the latter view, becoming president in his own right and not "Vice President, acting as President" as Harrison's cabinet was inclined to label him. Secretary of State Webster raised his concern about the constitutional implications of the succession with William Carroll, clerk of the Supreme Court. Carroll conveyed Webster's misgivings to Chief Justice Roger Taney, reporting that the "Cabinet would be pleased to see and confer with you at this most interesting moment." Taney responded with extreme caution, saying that he wished to avoid raising "the suspicion of desiring to intrude into the affairs which belong to another branch of government."
Tyler argued that his vice-presidential oath covered the possibility of having to take over as chief executive and consequently there was no need for him to take the separate presidential oath. The cabinet, major newspapers, and some Tyler advisers disagreed. To remove any doubt, despite his own strong reservations, Tyler agreed to the oath, which was administered on April 6 at Brown's Indian Queen Hotel by Chief Judge William Cranch of the U.S. Circuit Court for the District of Columbia.
In his first moves as President, Tyler set the stage that he would assume full duties as President, not merely be a figurehead until the next election:
In his first official move, Tyler convened Harrison's cabinet and listened patiently as Secretary of State Daniel Webster advised that it had been Harrison's custom to bring all administrative issues "before the Cabinet, and their settlement was decided by the majority, each member of the Cabinet and the President having but one vote." Choosing his words with care, Tyler responded, "I am the President, and I shall be held responsible for my administration. I shall be pleased to avail myself of your counsel and advice. But I can never consent to being dictated to as to what I shall do or not do. When you think otherwise, your resignations will be accepted."
When Congress reconvened, they argued the point themselves:
As the epithet "His Accidency" grew in popularity, Congress convened on May 31, 1841, for its previously called special session and immediately took up the issue of Tyler's claim to be president in his own right. The question was raised as the House prepared a resolution authorizing a committee to follow the custom of informing the president that "Congress is now ready to receive any communication he may be pleased to make." One member moved to amend the resolution by striking out the word "President" and substituting "Vice President now exercising the office of President." Members more sympathetic to Tyler's reading of the Constitution — and the need to get on with the business of the nation — offered a firm rebuttal, which the House then agreed to.
In the Senate, on the following day, a member posed a hypothetical question as to what would happen if the president were only temporarily disabled and the vice president assumed the office. He envisioned a major struggle at the time the disabled president sought to resume his powers, particularly if he and the vice president were of different parties. Senator John C. Calhoun reminded the Senate that this was not the situation that faced them, rendering further discussion pointless. And what about the Senate's president pro tempore? Should he assume the vice-presidency as the vice president had assumed the presidency? Former President pro tempore George Poindexter urged the incumbent president pro tempore, Samuel Southard, to claim the title. Southard ignored the advice, and the Senate then joined the House in adopting a resolution recognizing Tyler's legitimate claim to the presidency.
There is a lot more information on the site I linked about Tyler’s political career, both as President and before to help you make an informed choice on our poll! You can also research the other choices (or more on Tyler if you like) on our poll by clicking on their name in our subject index (scroll down on the right side - it is called "Labels").