Okay with the sad death of John Spencer, Leo is going to disappear from The West Wing in a few weeks. Now how he will be replaced depends on when his character (presumably) dies. The six main periods of time possible are:
1) Before the election and in time for a new name on the ballots
2) Before the election, but too late for the ballots to be changed
3) After the election, and before the electoral college meets
4) After the electoral college meets and before the Congress the votes
5) After Congress counts the votes, and before Inauguration Day
6) After Inauguration Day
Scenario 1 is simple. It varies a bit state by state but if the death occurs 60 days before the election, then the state party can substitute a name on the ballot.
Scenario 2 is fairly straight forward also. McGarry’s name would remain on the ballots, but any votes cast for him will still be valid for his electors for the Electoral College. The Federal Party will have nominated prior to the election a replacement candidate, and the electors would vote for the replacement candidate. This happened in 1912 with the death of he Vice President James Sherman on October 30th, 1912, a few days before the Presidential election. The GOP selected Nicholas Butler as his replacement. They lost incidentally.
Scenario 3 is more complicated. If the candidate dies after election day, and before the electoral college vote there is no “moral” mandate for the candidate. In 1872 presidential candidate Horace Greeley died after the election on November 29th. His electors split five ways with 42 votes for Senator Thomas Hendricks, 18 for Vice Presidential nominee B. G. Brown, a few votes for two other candidates and five votes for the deceased Horace Greeley. These latter votes were disallowed by Congress. Now as Greeley lost, it was not that significant. As McGarry is a VP, not a presidential, candidate one would assume Santos would ask the electors to vote for a person he chooses. They would however in theory have a free vote.
Scenario 4 which has McGarry die after the electoral college votes is even more murky. I am unsure if Congress can certify a dead candidate. The common sense answer is Congress certifies no Vice-President due to the death of the winning candidate. However a weaselly politician could try and argue that with McGarry dead, he is an invalid candidate and hence the next highest polling VP candidate (the Republican VP candidate) has to be certified by Congress. This could be a great plot line with Santos having a religious right Republican as her VP. Remember in TWW the Republicans control both the House and Senate so could arguably certify it that way.
Scenario 5 is clear. If after certification of the vote McGarry dies, there is a vacancy. It can’t be filled until after Inauguration Day however.
Scenario 6 is the most routine. McGarry dies as the Vice-President. Under Section 2 of the 25th amendment to the US constitution, Santos will nominate a new VP, which requires a majority confirmation from both Houses of Congress.
According to USA Today five episodes have been filmed ahead of what has already showing in the US. With the Xmas break this will last until 19 March. The 8 January show is the one of the Vice-Presidential debate including Spencer. I suspect they will do a tribute to him with that broadcast.
They also report the election result has not yet been filmed, so that makes scenario 1 or 2 more likely. Scenario 4 would be a good plot twist though!