From WSJ:

Earlier this month the Administration suggested that it may grant a waiver for some insurance plans from a tax that is supposed to capitalize a reinsurance fund for ObamaCare.

The unions hate this reinsurance transfer because it takes from their members in the form of higher premiums and gives to people on the exchanges.

The unions ought to consider this tax a civic obligation in solidarity with the (uninsured) working folk they claim to support. Instead, they've spent most of the last year demanding that the White House give them subsidies and carve-outs unavailable to anyone else.

And as I've posted before, the average union worker is a racist, homophobic, xenophobic, misogynist knuckle dragging cretin.

There are other ways to make the unions happy.

I expect the final immigration bill will include a requirement that
all undocumented workers applying for legal status must join a union.

Solidifying the democrats oldest and newest voting bases.

If that happens there will be strong argument for outlawing unions.