A stealth effort in state legislatures would essentially eliminate the Electoral College and undermine the carefully considered structure set up by the Framers to elect our president.  And it would do so without amending the Constitution.
Many Americans may forget that when they vote in November, they are not voting directly for the candidates.  Instead, under Article II, they are voting for electors who have pledged to vote for particular candidates.  Each state has electors equal to the number of senators and representatives the state has in Congress.  Thus, even the smallest states with the least population, places like Montana and Vermont, get at least three electors (as does the District of Columbia).