At any point from 1900 onwards, would it have been possible and indeed realistic for a sitting US Vice President to either challenge their President in the primaries/at the convention or to run as a third party candidate against their President. In addition, would it also have been possible for the VP to refuse to resign from office (legally they are within their rights) and still mount an electoral challenge to their President?
OK, let's grant that 1940 was a unique situation--the unprecedented nature of the third term, FDR's bring coy for a long time on whether he would run again, etc. Can we think of some other possibilities?
Maybe if Gore-Lieberman is elected in 2000, and Gore doesn't go to war with Iraq (I happen to think Gore would, but that's a debate for anther day) Lieberman runs against him in 2004 in protest?
Or Hiram Johnson accepts Harding's alleged offer of the vice-presidential nomination in 1920 (doubtful), the convention accepts him (more doubtful), the ticket is elected (a virtual certainty) and Harding manages to live until 1924 (unlikely but possible)? Does Johnson challenge Harding as both too scandal-plagued and too conservative?
No 22nd Ammendet
Clinton tries to run for a third term
It's always been Gores dream to be president
How about Obama chooses Clinton as VP, and a major scandel/event causes Clinton to resign and Primary Obama?
One possibility that springs to my mind is that Reagan and Ford hammer out a deal in 1980 for a "co-presidency" ticket. If they manage to win in the fall (no sure thing, in my opinion) then Ford is stuck as Reagan's VP. The two men were not very fond of one another to say the least, so I could see Reagan backtracking on parts of his deal with Ford or pursuing policies with which Ford did not agree with a "what's he going to do about it" attitude. If tensions are high enough, Ford could resign in protest to some of Reagan's more conservative policies, be made aware of the fact that he would be dropped from the ticket in 1984, or essentially be stonewalled by the administration and sent overseas to visit the countries of the world in alphabetical order from Afghanistan to Zimbabwe. Either way Ford isn't going to be happy with Reagan and might decide along with a few other Republicans to mount a challenge during the primaries.
Actually, I could see Ford getting together with some other disgruntled Republicans to run Ford as the "national" candidate where he would do well but letting others run as favorite sons of their states or regions in order to win a significant enough block of delegates at the convention to block Reagan's renomination. It would make for a fun timeline.
One possibility that springs to my mind is that Reagan and Ford hammer out a deal in 1980 for a "co-presidency" ticket. If they manage to win in the fall (no sure thing, in my opinion).
Alternatively, have Gore win but pick someone other than Lieberman who is bitterly opposed to a Gore decision to invade Iraq. Said VP resigns in protest and runs as an anti-war candidate in the primaries.
Carter picks Kennedy in 1976 instead of Mondale. Not sure if that would ever happen, but let's just say for the sake of this post it does. Carter picks Kennedy, runs to the right in his presidency, isolates Kennedy, who feels useless, especially in the healthcare fight (Kennedy felt he should be included in the debate and push to get something passed with his ties in the Senate). Everything goes to hell like in reality, Kennedy announces he's running to unseat Carter in the 1980 primary.
I doubt this is viable considering Kennedy's baggage is way too much for Carter, who was morally conservative and probably turned off by Kennedy's alcoholism and philandering. But...
I know this is not the main point of your post, but I'm curious why you think a Reagan-Ford ticket's victory would be "no sure thing." Reagan-Bush won by almost ten points in OTL. I see no reason at all why Reagan-Ford would do substantially worse--let alone ten points worse. Some people on the right wing of the GOP were upset by the thought of Ford on the ticket, but they were also upset by the choice of Bush. As for the general public, they almost elected Ford in 1976 and probably thought more highly of him in 1980 after four years of Carter. In fact, some moderate Republicans who voted for Anderson in OTL might vote for Reagan if he had Ford on the ticket.
It may be an exaggeration to say that "Nobody votes for the veep" http://www.slate.com/articles/news_...minute/2000/06/nobody_votes_for_the_veep.html but most political observes are convinced that the choice of a running mate sways relatively few votes. It can matter in a close race, but 1980 was not close.
OMG. Someone make this and PM the link PLEASE. Ford = Grover Cleveland 2.0 with the Reagan Revolution's head being cut off. Anything. That would be such a cool story. (Maybe Rumsfeld becomes Reagan's second VP candidate if he wins or decides to run independent)
Actually, that brings up a point. If the President is defeated by his party, he may just decide to run on something dubbed along the lines of the National Ticket for reelection.
If you look at the people who were most talked about as running mates for Gore in 2000--Gephardt, Kerry, Graham, Bayh, etc.--none of them seems dovish enough to challenge Gore over going to war with Iraq (though it is true that Graham did vote against authorizing use of force). http://usatoday30.usatoday.com/news/e98/e2315.htm