"What about the Republicans that were against the Colorado Plan?"
The Colorado plan was even worse than the proposed California plan. The California plan would apportion the electoral votes by congressional district, while the Colorado plan would have split EVs based on proportional representation. For example, if Colorado adopted the plan proposed in California, Bush would have won 7 of the state's 9 EVs, but had Kerry managed to carry the state Kerry would have won 6 or 7 of the state's 9 EVs; under the plan proposed in Colorado, the candidate who carried the state would have won only 5 EVs (to 4 for the loser) unless he carried the state by over 10%, and would not get more than 6 EVs unless he held the loser below 33%. The California plan being adopted in Colorado would result in the state still being contested, while the adoption of the Colorado plan would mean that no presidential candidate would ever pay attention to Colorado.
Never the less, it would be very interesting to see all the large states (lots of EVs) adopt a plan whereby their power is reduced in favor of small states. I can see how small states would not like the plan, large states can adopt it as a pure suicide play. I believe this is just an example of republicans being sarcastic.