Leading article: An unlikely rediscovery of union muscle

Today the stand-off between the Wisconsin state government and its public-sector trade unions could come to a head. The battle is between a Republican governor intent on curbing the benefits and power of the unions and tens of thousands of public employees, supported by Democratic legislators, who are determined not to lose their jobs, pay or bargaining rights.

So far, so conventional. But two things make this dispute unusual. The first is its duration, solidity and potential reach. Fearful workers in other Midwestern states, where Republicans have majorities in the new legislatures, are either taking or contemplating action of their own. The second is the way that the unions have latched on to the ferment in the Arab world and claim to be standing up not just for workers' rights, but for a more equal society and enhanced democracy. Questioning the democratic credentials of the United States is not something America's de-fanged trade unions do as a matter of course.

Thus far, there is no sign of either side giving ground, and the longer the dispute goes on, the more triumphantly it is hailed – in the US and abroad – as signifying variously a new dawn in American politics, the rebirth of US trade unionism, or the advent of a European-style political left.

There is certainly room in American politics for a more vocal articulation of social justice, and Barack Obama's election to the White House may have heralded a longer-term political shift. But to see the workers' protest in Wisconsin as evidence that a somnolent left is awakening to parry the Tea Party movement on the right is likely to be premature. It rather exposes how deeply US politics is now polarised. The country as a whole shifted to the right in last year's mid-term elections, and Wisconsin has a budget-cutting legislature because that is what the state's voters chose.

It is refreshing to watch US unions rediscovering some muscle, but unrealistic to expect that President Obama will be able to rely on a resurgent left when he seeks re-election in 2012. The shrinking centre, once again, is where victory will be found.