If you want to know how the implementation of President Obama’s health care law will go next year, California is a good place to watch. Anticipating problems with the national implementation of the law, some liberals have pre-emptively tried to do pin the blame on recalcitrant Republican governors for putting up roadblocks. But California, in addition to being the nation’s largest state, has been an early adopter, enthusiastically deciding to start setting up exchanges and participate in the Medicaid expansion. So, any problems California runs into will be hard to blame on Republican intransigence.

That’s why it has to be troubling for Obamacare supporters that, as Conn Carroll noted earlier, the nation’s largest health insurer, UnitedHealth, has declined to participate in the state’s subsidized health exchange. Other large national insurers, Aetna and Cigna, also declined. In the absence of large national insurers, the California exchange will be dominated by Kaiser Permanente and Anthem Blue Cross and Blue Shield of California — which already control 87 percent of the state’s insurance market, according to the Los Angeles Times.