Was Nixon eligible to run again?

Not so. Most chief justices have been appointed directly to the position , as Roberts was.

From the Wikipedia article on the Chief Justices:

the major difference that a president is elected, presumably demostrating the will of the people at the time, so can claim a mandate. Whereas a Queen or Governor General holds no such mandate in modern society. They are more like an emergency kill switch than a speed governor, so to speak. This is why I think it is a bad idea for Canada to get rid of the monarchy - then we’d replace that with an elected “used politician” as head of state with political baggage and delusions of mandate.

Similarly, impeachment was viewed as a last resort to remove a leader who had seriously violated the norms of office - until Andrew Johnson where it became and overtly political act, and because that failed, it stayed that way until Richard Nixon. For him, even the realistic threat that impeachment would succeed was an indicator he should leave. Since then, it’s been more a political tool.

No, they can’t. The line of succession is defined in the Constitution. If they impeach the President and VP, the Speaker of the House becomes President. Which presumably would be acceptable to the majority of Congress, but they can’t just put anyone they want in as President.

It does seem like that would theoretically be a way around the term limits, though; you can’t serve as VP if you’re not eligible to be elected President, but no such rule applies to the Speaker.

The Constitution only defines presidential succession up to the Vice President. After that it’s up to Congress.

Article II section 1 clause 6

In Case of the Removal of the President from Office, or of his Death, Resignation, or Inability to discharge the Powers and Duties of the said Office, the Same shall devolve on the Vice President, and the Congress may by Law provide for the Case of Removal, Death, Resignation or Inability, both of the President and Vice President, declaring what Officer shall then act as President, and such Officer shall act accordingly, until the Disability be removed, or a President shall be elected.

~Max

You’re right. I had thought the 25th Amendment spelled out the line of succession for some reason, but it doesn’t. It’s defined by the Presidential Succession Act passed by Congress under the authority of Article II, and so could be changed at any time with a simple majority.

Ignorance fought!!

For that matter, the House can choose whomever they want as Speaker, too (it doesn’t even need to be a member of the House).

The current succession rules do provide that if anyone in the line of succession is ineligible for the Presidency, that person is just skipped over. But that’s just an act of Congress, too.

So they impeach the president. Then the VP gets the choice - nominate Joe Schmoe as VP and resign, or we impeach you too. If they have to impeach the VP as well, the the speaker becomes president, nominates Schmoe as VP, and once congress approves that, (s)he resigns. Presumably a congress with the majority enough in both houses to pull this off also includes a speaker in on the game.

So it could theoretically be done. But it’s realistically very unlikely that the voters would ever actually elect a President of one party and then two years later give the other party a 2/3 majority in the Senate. If that did happen, it would reflect such a massive shift in public opinion that the President would likely be unable to effectively govern anyway. The only time we’ve ever come close to that was Andrew Johnson in the immediate post-Civil War period (though of course Johnson had never actually been elected President).