What Constitutional duty?”
You will find that many in this forum have been working for more than a year to understand the issues, discover the facts and speak knowledgeably about the matter. Some of us did not come along until a month or so prior to the primaries.
Fortunately for all of us, some of the material has been on the record for decades; for instance, 3 USC 15.
The duty I refer to is found in the 20th A.:
...if the President elect fails to qualify...