What happens if no one in the line of US presidential succession is eligible to become president?

Question

As I understand it, should the president of the US die/become unfit for office, the vice president would become president, and if the vice president (now president) were to die/become unfit for office, the Speaker of the House would become president and so on, down the line of succession.

According to the 12th amendment of the US constitution, the VP candidate must meet the same requirements as the presidential candidate.

My question is, what happens in the unlikely case where both the president and vice president die/become unfit for office and no one in the line of succession is eligible? For example, every person is a naturalized but not natural-born citizen (Elaine Chao, the current Secretary of Transportation, was born in Taiwan but became a naturalized citizen, and is thus ineligible to become president)

Answer 1

The Constitution does not allow for anyone who is not a natural-born citizen to become Acting President, even in this scenario. So Elaine Chao would still not become Acting President.

Neither the Constitution nor the United States Code specify what would happen if the entire line of succession is exhausted. This is why everything possible is done (notably having a designated survivor for events such as the State of the Union) to prevent it from happening. Some recommendations have been made on how to fill this gap, but as of this writing, none have been implemented.

Answer 2

Background

There are three positions in the line of succession where candidates must be eligible to be president:

1. President.
2. Vice president.
3. President pro tempore of the Senate.

President should be obvious. Vice president is a little clumsily stated, but the general rule is that a vice president is just a president waiting to happen. The President pro tempore of the Senate has two duties:

1. Presiding over the Senate when the vice president is not available and there is no other person delegated with that power. This is almost always handled by delegating that power.
2. Taking over in the case that the president, vice president, and Speaker of the House all become incapacitated.

As such, choosing a President pro tempore of the Senate who is not eligible to be president would be silly. It's a post with a few ceremonial duties that can be delegated and one responsibility that cannot. Choosing someone incapable of fulfilling the one responsibility may be legal but it makes no sense.

So as a practical matter, these three positions are always selected for eligibility to be president. The only way that this could occur would be for all three positions to be unavailable. For example, these three might be in a single meeting and all killed at once.

Scenario

The presumption here is that every other position in the line of succession would not be qualified (or also dead).

Solution

The obvious solution would be to declare a different Speaker of the House or President pro tempore of the Senate. These positions are controlled by the House and Senate respectively. They require no presidential input nor input from the other chamber. So long as either chamber has a quorum, it could appoint someone by a simple majority vote (which may change any current rules with other requirements).

Now, what would happen if there was no quorum? For example, if Washington, D.C. had been hit by a nuclear bomb, it might easily have wiped out the entire line of succession and both chambers of Congress (possibly leaving someone like Elaine Chao who is ineligible to become president).

In a case where Congress was not available, states have the ability to appoint Senators temporarily. So enough state governments would have to appoint replacement Senators to allow for a quorum in the Senate, which could then appoint a President pro tempore of the Senate. That person would then become acting president. As acting president, that person could nominate a vice president. Congress could approve the nomination (possibly after a bunch of special elections to fill the House). The vice president would be ahead of the President pro tempore of the Senate in the line of succession and would become president.

It would likely be easier to appoint acting Senators than to elect House members. So I am assuming that the Senate would reach a quorum first and select someone to be acting president.

This process assumes that the Speaker of the House would decline to replace the President pro tempore of the Senate as acting president. Because otherwise the Speaker of the House would be higher in the line of succession. The House could instead choose someone specifically to become acting president and replace the President pro tempore of the Senate. But they might not do that, as there may not be anyone who wants to give up a position in the House to become acting president.

Either the acting president (while serving) or the new president (once the oath of office is taken) could refill the line of succession by appointing a new cabinet.

Answer 3

First, assuming that their is no other death in the lines, the Vice President must meet the same qualifications as President to hold the office of Vice President, thus at least one person holds the proper credentials of being a birthright citizen and the first "next in Line" step is not disqualified. As you mentioned, at the lower levels this excludes that person from their spot in the line, with everyone below that office moving up in the chain. In addition, the disqualified cabinet member is never the secret service's pick for the "Designated Survivor" as the point of the position is to be alive in the event of a decapitation strike on the line of succession in a common gathering (i.e. the state of the union).

In addition to your mentioned current example, Secretary of State Henry Kissinger is the highest in office to be disqualified, (fourth) under the current rules, though from July 9 through July 11th of 1850, the second in line was disqualified as John Tyler's death and accession of Millard Fillmore leaving a vacancy in Vice President, and an unrelated vacancy in President of the Sennate Pro tempore, Speaker of the House, Howell Cobb, was not yet 35 years of age and thus disqualified from holding the office of the presidency. It is the only time where the line of succession was empty despite at least one office being occupied and only one of three times where the line was non-existent while the law had a say on the matter (there were two times after this where the Preisdent's death occurred during a time with no President pro Tempore and no Speaker of the House.).