It looks as if one of the largest Democratic interest groups in the country is less than happy with the Obama administration:

For two years as a presidential candidate, Barack Obama addressed educators gathered for the summer conventions of the two national teachers’ unions, and last year both groups rolled out the welcome mat for Education Secretary Arne Duncan.

But in a sign of the Obama administration’s strained relations with two of its most powerful political allies, no federal official was scheduled to speak at either convention this month, partly because union officials feared that administration speakers would face heckling.

The largest union’s meeting opened here on Saturday to a drumbeat of heated rhetoric, with several speakers calling for Mr. Duncan’s resignation, hooting delegates voting for a resolution criticizing federal programs for “undermining public education,” and the union’s president summing up 18 months of Obama education policies by saying, “This is not the change I hoped for.”

“Today our members face the most anti-educator, anti-union, anti-student environment I have ever experienced,” Dennis Van Roekel, president of the union, the National Education Association, told thousands of members gathered at the convention center here.

A little context here: During the campaign, President Obama came out in favor of merit pay for teachers -- this was a big step for a Democratic presidential candidate. (In '04, Kerry first came out in favor of merit pay and reversed his position in the middle of the campaign after the teachers' unions took him to the woodshed.)  Still, Obama didn't entirely abandon the favored Democratic constituency. Shortly, after he was elected the Obama administration killed off the D.C. school choice program, which appeared to be a nakedly political move designed to appease the unions.

But increasingly, the teachers' unions continued opposition to charter schools, school choice programs, merit pay and just about every other proposed educational reform under the sun is alienating voters across the political spectrum. There are no less than three documentaries about America's broken edcuation system coming out this year -- including one from the producer of An Inconvient Truth -- and every one of them paints teachers' unions in a negative light. If teachers' unions are now upset that the Obama administration isn't toeing their line and Democrats feel increasing empowered to embrace eductaion reform rather than the unions' campaign cash, that's probably a good thing.