Washington DC has 3 electors, 3 whom I will ignore since they were added, specifically for DC, in the 60's.
All other ECV (Electoral College Votes) are determined by the same formula
Senators + Members of the House.
There have been proposals to see the entire EC go to a proportional method, but this often has opposition as it takes away some of the power smaller states have. Currently, if you win a small state by a small share of vote, you win all of the ECs, whereas under this method, a candidate is almost guaranteed at least 1 of the 3.
This proposal will mean that if you "win" the "state", you also win the 'senate ECVs'.
Lets say someone wins Wyoming by 51% vs 49% for their opponent, that person would win the 2 "senate" votes, and this happens before any proportional calculation is carried out. In this example, since there is only a single proportional seat, the person who takes 51% would win all 3.
This will ensure that the smaller states still matter, if not matter even more, since any state with 4 or more EV's might end up split, while the 3 EV states would retain their winner-take-all methods.
Washington State has 12 ECVs. Lets presume that one candidate wins the state by 60% over 40% for the other.
The winner would take the 2 "senate" votes, plus 6 "proportional" votes, for a total of 8, while the loser would take 4 proportional vote for a total of 4.
Why use this system and not full-out proportional ECVs? or full out proportional without ECVs?
Simple. I'm not writing this because I desire to waste my time, or I wish to explore a fantasy universe where such proposals are easily turned into laws. I'm writing this because I believe it has a far better chance of becoming law than any "more pure" proportional system does.
In short, this proposal is "more electable" than many other proposals, and hence why I feel it is the best possibility.