Re(2): Colorado to Change Method of Casting Electoral Votes Posted on 2/24/2019 at 22:34:37 by Bill Crawford, (14)
The below-linked article presents the other side of the argument.
As indicated in the below-linkled article, it looks like this is constitutional; this, because the 12th amendment nailing down how the electoral college works, doesn't specify how a state's electors' votes shall be governed--except that they cannot vote for a president and a vice president from the same state; i.e., each state can vote its electors as it sees fit.
It looks like the only way to prevent a state's electoral votes from going to the presidential candidate receiving the largest national popular vote would be by means of an amendment to that state's constitution stating the the state's electoral votes would go to the presidential candidate receiving the largest popular vote in that state
P.S. I just found another site (see below:http://archive.fairvote.org/?page=967) which says that twenty-nine states (including Colorado) currently have laws stating that the state electors must vote for the candidate receiving the largest number of popular votes in the state---But, as can be seen by the latest turn of events in Colorado, those laws can be changed; ergo, the need for an amendment to the state's constitution.