For the hard-pressed American trade union movement, with a membership of only 7 percent in the private sector while 36 per cent of public sector workers are union members, today’s recall election in Wisconsin is a moment of do or die.

Wisconsin’s voters will decide whether the Republican Governor Scott Walker, elected governor in November 2010, is fired or allowed to serve out his term after ramming through a new law revoking the collective bargaining rights of the State’s public employees.

The battle in Wisconsin has been going on for over a year and has mobilized all the political forces in the State, where in 1959 as the first State ever, the right to collective bargaining for public employees was established. In the process, Wisconsin has become the epicenter of the fierce ideological struggle in today’s American politics.

Only three times in history have American voters gone to the polls in so-called recall elections to decide on whether the State’s governor will be fired or get to continue to serve out the term.

The first recall election took place in North Dakota in 1921, when voters ousted Governor Lynn Frazier. Then followed California in 2003, when Democrat Gray Davis was voted out, paving the way for Arnold Schwarzenegger as the new governor. In both states, the recall elections were the result of angry conservative Republicans, while the Wisconsin election is the result of an angry union movement. All three elections resulted in fierce battles between the right and the left — in the first two, the right won.

The campaign has become the most expensive ever in Wisconsin. Over 63 million dollars have been spent in the fight between Walker and the challenger, Democrat Tom Barrett, Mayor of Wisconsin’s largest city, Milwaukee. Lots of money has rolled in from across the country. Of Walker’s 30 million dollars, two-thirds come from wealthy conservative forces outside of Wisconsin, while Barrett is far behind with 4 million, a quarter of which from out of state.

Walker leads in the polls by an average of 6.7 percent, so he is favored to win, according to the New York Times blog FiveThirtyEight. An unusually high turnout is expected, about 65 percent, which usually favors the Democrats. But in Wisconsin, voters on both sides so motivated that it is difficult to say who will benefit from voter mobilization.

A Walker victory will encourage the Republicans leading up to the presidential election in November, but President Obama’s victory in Wisconsin is probably not in danger. He currently leads over Mitt Romney in the polls by an average of 4.7 percent. Obama won there in 2008 and in Wisconsin, the Democratic candidate has won in every presidential election since 1988.