Neither Martin Luther King nor Rosa Parks were interested in running for President.
They had other work to do, and I bet they both knew they were neither qualified nor, at that time, electable for that office.
I never, ever voted for Reagan, but I understand his personal attractiveness, even though he oversaw Iran-Contra, which made Watergate look like schoolboy pranks.
After what the Republicans have done to the Dept. of Justice, they would have to resurrect Theodore Roosevelt (and persuade him to run, which might be a hard sell to the man who established the national park system) for me to vote for a member of that party for President.