The results of the election are not confirmed yet.
But what if Biden dies and he wins before results declared?
Does the Democratic Party have to nominate a new president? Would that mean that Trump wins? Or what?
For the purpose of this question I assume Biden wins (as of time of writing, he hasn't).
Four key dates matter here: election day on November 3 (voting is already underway in most states); the electoral college votes on December 14; a joint session of the new Congress on January 6 to count those electoral votes and certify the results; and Inauguration Day on January 20 to install the winner as president. A death or permanent incapacitation at any point along that timeline would create different outcomes, all freighted to different extents by politics.
Many analyses, including one from the nonpartisan Congressional Research Service, agree that if a candidate dies before election day, the party that nominated him or her would designate a successor — most likely the party’s vice presidential nominee — and the votes would be counted as if the candidate were still alive. The results would then accrue to the late candidate’s running mate. But each state has its own rules for how to handle the vote, some with more foresight and imaginative planning than others, which could launch a barrage of legal challenges and political maneuvering.
Similarly, if the winner of the most electoral votes dies between election day and December 14, the day each state’s electoral voters meet to cast their ballots, by most assessments the states could require the electoral votes go to that candidate’s running mate — but that is not set in stone in every state. Again, cue the lawyers.
Most relevant part highlighted.
If Kamala Harris were also to die, then the Democratic party would have to nominate a new successor - presumably Bernie Sanders, the runner-up in the primaries, but no guarantee.