Democratic partisans are fond of saying that anti-immigrant measures advanced by Republicans are good for Democrats because they alienate a large Latino population that would otherwise be inclined to vote Republican (see e.g. "Even More Opportunities for GOP Latino Alienation").
The Republican anti-union showdown with public employees unions playing out at the moment in Wisconsin (and the Denver Post's AP story advises me in other states across the country like Ohio, Tennessee, Indiana, Nevada and Florida) may have a similar effect.
One of the crucial sources of the big Tea Party wins in 2010 was union member ambivalence about voting for Democrats. While Democrats have near unanimous support from the leadership of organized labor, union members themselves barely favored Democrats more often than Republicans in 2010 election in many key races.
But, the current multi-state Republican jihad against labor unions, whether or not it is successful, may change that in 2012. By reminding the public that the Republican brand hates unions and favors making deep spending budget cuts substantially on the back of union member compensation, the Tea Party union members of 2010 may return to the Democratic fold in 2012.
Half of union members in the United States are public employees who are directly affected by the stance Republicans have taken in Wisconsin, and the other half don't have to be particularly prescient to see Republican attacks on public sector unions translating into attacks on their economic interests should Republicans gain control of the federal government as well.