WHAT SPECIAL INTEREST is spending the most money to influence the 2010 election? The answer isn't the US Chamber of Commerce, notwithstanding President Obama's recent attacks on the Chamber's campaign contributions. Nor is it the Karl Rove-backed network of pro-Republican campaign organizations, including American Crossroads and Crossroads GPS, that have also been assailed by the White House and the focus of critical media attention.

In reality, the biggest outside spender is the American Federation of State, County, and Municipal Employees, which is pumping almost $88 million into TV commercials, phone banks, and mailings to promote Democratic candidates.

"We're spending big," AFSCME President Gerald McEntee boasted to The Wall Street Journal. "And we're damn happy it's big. And our members are damn happy it's big -- it's their money."

AFSCME isn't the only public-sector union "spending big" to influence the vote on Nov. 2. So is the National Education Association (NEA) and the Service Employees International Union (SEIU), respectively the nation's largest and fastest-growing unions. Together, the three government-employee unions will have spent nearly $172 million campaigning for Democrats in the course of this election cycle. That outstrips by more than $30 million what the Chamber of Commerce and the Rove network combined are pouring into the 2010 campaign.

I have no objection to close media scrutiny when business-linked organizations spend heavily on campaign ads. But it should be a far bigger story when public-employee unions do so. Indeed, it should be serious cause for concern...