[xzins]

My memory can’t recall anything in the Constitution that requires a winner-take-all system. I don’t know the history of the electoral college in this matter, though.

Did the early republic also have a winner-take-all system?

[rhinohunter]

Constitutionally, the legislature has broad latitude to appoint the electors. However, once they declare a popular election to determine the electors, as all 50 legislatures have done, they become very constrained by Federal Election Laws.

I'm no expert on Federal Election Law, but I doubt that Maryland's scheme would hold up to a challenge.