Thanks to the public employees of Wisconsin, thousands of whom have occupied the state capitol building for the past several days, the class struggle has returned to the United States. Of course, it never really left, but lately only one side has been fighting. Workers, their unions and liberals more generally have now rejoined the battle.

As many commentators have pointed out, Governor Scott Walker’s plan to eliminate most collective bargaining rights for public employees’ unions has nothing to do with Wisconsin’s fiscal problems (which are far less serious than those of many other American states). Instead, it represents the culmination of a long right-wing effort to eliminate the power of unions altogether. During the Great Depression, Franklin Roosevelt redefined American politics by forging a majority political coalition that included labour unions, white ethnic minorities (Irish, Italians, Jews), African-Americans in the North, liberal intellectuals, Southern whites and, after the passage of the Social Security Act in 1935, the elderly. The New Deal coalition proved powerful enough to enable Democrats to win seven of the nine presidential elections between 1932 and 1964. One of its key achievements was the Wagner Act of 1935, which gave most workers the legal right to form trade unions.

The Wagner Act did not apply to people employed by state and local governments. Their rights are a matter of state law, and Wisconsin in 1959 was the first to give public employees the right to collective bargaining. The state has a long tradition of political liberalism, dating back to Robert LaFollette, a leader of the Progressive movement of the early 20th century. But Wisconsin was also the home of Joseph McCarthy, and its conservative persona is now in the political ascendancy.

In the past generation, the percentage of American workers who belong to unions has declined precipitously, not only because of concerted attacks by right-wing politicians and the corporations that fund them, but also because of deindustrialisation. Indeed, public employees have been the only group among whom union membership has risen.

Ever since Ronald Reagan destroyed PATCO, the union representing air traffic controllers, the right has had public unions in its sights. The financial crisis has given conservatives the opportunity to blame the supposedly lavish salaries and pensions of teachers, policemen and social workers for the states’ economic ills, even though those ills are just as serious where public employees lack collective bargaining rights.

Sadly, until Wisconsin, leading Democrats have had little to say in defence of unions, even though, despite their weakened condition, they’re still an important part of the party’s base. President Obama has criticised Walker. But he has been far less outspoken about the struggle for democracy at home than he was (belatedly) about events on the streets of Egypt. Representatives of the American black elite, Obama among them, tend to share the free-trade, finance and technology-oriented economic outlook of upper-class whites, in which unions play little part. Like Jimmy Carter and Bill Clinton before him, Obama has shown no desire to promote legislation demanded by unions that would make it easier for workers to organise, or to address the problems that defined New Deal liberalism and remain all too relevant today: economic inequality, widespread unemployment and unrestrained corporate power.

So it has been left to grass-roots activists to respond to the latest Republican assault on unions. And despite the recent demonisation of public employees as living lavishly on the backs of hard-working taxpayers, most Americans still respect policemen, firemen, teachers and other public workers. This is one reason the demonstrations in Wisconsin seem to have generated widespread support across the country. Walker has threatened to send in the National Guard to clear the capitol of protesters, a throwback to the days when troops were regularly employed to crush strikes. It will be interesting to see whether the American military, unlike its counterparts in Egypt, is willing to use violence against fellow citizens demanding their rights.