California’s fiscal crisis is in danger of becoming a serious headache, not just for the state and its feuding politicians in Sacramento, but for the entire nation.

In public, federal government officials talk about California’s problems as if they were ringfenced – a crisis for the state but with few national ramifications. They know the slightest whiff of federal intervention would take away the incentive for California’s politicians to agree on tough spending cuts and tax increases.

But they know they cannot ignore a fiscal crisis in the most economically important state in the middle of a global financial crisis. So they are keeping a careful eye on events and it would be surprising if they were not also reviewing the options at their disposal to mitigate the damage.

California has a budget deficit of $26.3bn (€18.85bn, £16.18bn) on revenues of just $113bn, according to Keefe, Bruyette and Woods, a broking firm. It has a balanced budget rule that forces it to eliminate the deficit but no agreement as to how. It has already effectively decided to selectively default – paying vendors with IOUs rather than cash. Worse could follow if the impasse is not resolved soon.

The worst case scenario would be a default by the state which has $59bn in general debt, $8bn in bonds linked to securitised revenues such as tolls and $2bn commercial paper, according to Standard and Poor’s, the rating agency.

A California default would be a shock for fragile financial markets. While no other state is in quite as difficult a position, there would be danger of widespread contagion in US markets and beyond.

Default still looks like a so-called “tail risk” – a high cost but low probability event. California’s constitution makes debt service a high priority. Its main constraint is cash flow. The decision to pay bills in IOUs saves cash for debt servicing and that should be enough for now.

But it is not sustainable indefinitely. In the absence of a fix for the underlying deficit, vendors and banks will eventually lose faith in the value of the IOUs, forcing California to pay for vital services in cash instead. Moreover, there are institutional reasons why the budget gap is proving difficult to close. Aside from the absurdity of having to balance the budget in the midst of the worst recession in half a century, California’s fiscal flexibility is diminished by other statutory restrictions, mostly imposed by state referendums known as propositions.

These restrictions make it exceptionally difficult for the state to raise property taxes or cut basic education spending. About 25 per cent of revenue is, meanwhile, ringfenced.

If the gridlock continues for months and the risk of default escalates, it would take a brave Treasury secretary not to step in with some kind of guarantee, credit line or outright bail-out for California. The immediate outlays involved would not be vast compared with federal bail-outs for banks and carmakers.

Yet, the federal government could not help California without aiding other troubled states, and a de facto or even de jure federal guarantee for all state debt would add a huge fiscal burden. Nor is it clear what the exit strategy would be: if the federal government blinked this year, it presumably would blink again next year if the problems were not resolved.

The most likely scenario is that California’s feuding politicians eventually reach a deal to close the $26bn budget gap. But even then there would be ramifications. The state’s economy is already weak; unemployment is 11.5 per cent and the multiplier effects of $26bn in geographically concentrated spending cuts and tax increases could be high.

Moreover, as KBW highlights in a research note, cutbacks at the state level will put additional pressure on highly stretched counties and municipalities. Like the state, these entities have little latitude to raise revenues. State-level fiscal consolidation could easily lead to a rash of defaults at the local level, which could roil the market for municipal debt nationally.

If this happened, the federal government might have to support the municipal bond market, possibly through a guarantee scheme with risk-based pricing. Alternatively, it could decide the best antidote to state fiscal contraction is further federal stimulus.

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