As indicated on this Wikipedia page, if Al Gore won Florida and the presidency in 2000, his running mate Connecticut Senator Joe Lieberman, who was also running for senate re-election at that time, would have become Vice-president, thus making his senate seat vacant, which would have led to a 2002 special election.
If Al Gore won the 2000 presidential election, who do you think then Republican Connecticut Governor John G. Rowland would have appointed to replace Joe Lieberman in the Senate and would the Republicans have been able to keep this senate seat in 2002?
https://en.wikipedia.org/wiki/United_States_Senate_election_in_Connecticut,_2000