Labor bosses are joining the ranks of the grumpy Obama backers who have come to discover that all their millions and all their boosterism have gotten them precious little. The New York Times has even figured it out:

The nation’s union leaders said on Tuesday that they were “appalled” at remarks made by President Obama condoning the mass firing of teachers at a Rhode Island high school. Coming the day after union presidents sharply complained to Vice President Joseph R. Biden Jr. over stubbornly high unemployment, stagnant wages and the administration’s failure to do more to create jobs, the statement — voicing a rare vehemence toward a Democratic president — underlined the disillusionment of an important Democratic constituency. Because unions have been so crucial to the Democrats election after election, political experts say labor’s ambivalence, or worse, toward the Democrats could greatly deepen that party’s woes this fall.

Big Labor, we are told by Charlie Cook, is “very disappointed, whether it’s about card check or the effort to tax Cadillac health plans. … They’re really disillusioned. I think one by one unions will start getting engaged and helping out the Democrats, but it could be half-hearted.” For some $200M or more that they spent electing Obama, not to mention millions for Democratic congressional candidates, labor bosses thought they’d get something. Card check? Nope. Jobs? Not unless you count the two car companies Obama rescued. A sweetheart deal on health care? Unlikely. (But before the Obami fret too much, it seems that union bosses are still willing to pony up $53M of their members’ dues to help save the Democrats in Congress.)

Even if union bosses threw more millions into the Democratic coffers, the question remains whether they really can get their members engaged on behalf of a president and a Congress that has done so little for them. After all, union households went for Scott Brown in Massachusetts. Nor is Big Labor the only aggrieved member of the Democratic coalition:

Mr. Obama and the Democrats face problems among much of their base. Women’s groups are angry that some Democrats are pushing new restrictions on abortion as part of the health care overhaul. Many Hispanic groups are upset that Mr. Obama has not pressed for immigration reform this year. And gay and lesbian groups are unhappy he has not ended “don’t ask, don’t tell” as a military policy.

Hmm. So union leaders and members, liberal women, gays, and Hispanics, plus independents, fiscal conservatives, foreign-policy-establishment types, business groups, and Tea Party protesters have all had it with Obama. Some are angry because he’s proved to be ineffectual in pushing their liberal agenda, while others are miffed to discover that he’s, in fact, a statist (albeit incompetent) liberal.

Any president is bound to disappoint some supporters, but this one has disappointed more than his share. Granted, once the blank slate Obama maintained during the campaign was finally written on, some of the deluded Obamaphiles were bound to be disappointed. For those who fell for the candidate who promised to go line-by-line through the budget and pledged not to let Iran develop nuclear weapons, there’s a queasy realization that they were snowed. And for those like Big Labor who overestimated Obama’s ability to get their wish list fulfilled, there’s an awakening that they too were had. They thought they were getting a transformational president. Right now they’d settle for a minimally competent one.

Not all of the Obama-miffed will stay home or vote Republican. But many will. And if it’s a wave election, sweeping in Republican majorities or near-majorities in both houses, Obama may yet prove to be transformational. In just a couple of years he will have fundamentally altered the political landscape and shaken apart the Democratic coalition that was essential to his victory. Not the transformation he had in mind, of course.