Political parties set procedures for how to fill vacancies on the national ticket in the event that a presidential or vice-presidential candidate withdraws from the race or becomes incapacitated.
The Democratic National Committee outlines the process it uses to fill vacancies in its Charter and Bylaws. In the event of a vacancy on the national ticket, the Chairperson of the DNC, currently Tom Perez, would call a special meeting, and members of the DNC would select a replacement candidate.
Meanwhile, the Republican National Committee allows for two options for selecting a replacement candidate. The first option is for the members of the RNC to select a candidate. The second option is for the party to hold a second national convention. In that case, the party’s delegates would select the replacement candidate.
However, whether it is possible for a party to change a candidate’s name on the ballot depends on ballot certification deadlines set by the states. These certification deadlines have passed, and absentee and early voting in the 2020 presidential election have already begun in some states.
The Electoral College could assume an important role in the event that a presidential candidate becomes incapacitated after it is no longer possible to replace his or her name on the ballot. In some states, electors are not required by law to vote for the candidate who wins the popular vote in their state or district. These electors could vote for a replacement candidate that their political party has selected.
Other states do have laws that require electors to vote for the candidate who wins the popular vote in their state or district. However, it is a controversial legal question whether these laws are binding in the scenario where the winning candidate is unable to serve. Whether it is legal for electors in these states to vote for a party’s replacement candidate would likely be settled in the courts.