Anticipating concerns from experts who say the tax is a key part of controlling health care inflation and providing federal revenue to fund other parts of the Patient Protection and Affordable Care Act, Clinton promises that she will introduce reforms that will bring in revenue in other ways. 

"My proposed reforms to our health care system would more than cover the cost of repealing the Cadillac tax, while also reining in skyrocketing prescription drug costs and out-of-pocket expenses for hard-working families," she said in a statement Monday. "As president, I will continue to fight to make our health care system more value-driven and cost-efficient, and to drive down costs for patients and families."

And yet, the candidate has not specified what in her plan would bring in the estimated $90 billion lost by repealing the Cadillac tax. 

It's easy to see the political benefits of opposing the tax, which is opposed by a wide variety of interests, including unions and business groups.

And of course, millions of voters don't like hearing that their employer might be cutting benefits because of it, even if economists predict it will save the average American money in the long-run. 

Clinton, still considered the frontrunner for her party's nomination but no doubt concerned by polls that show Sanders running even or ahead of her in two crucial primary states, Iowa and New Hampshire, likely feels pressure to support the wishes of union members, a critical part of the Democratic Party base. 

And yet, unlike many calculations aimed at winning a primary, her rebuke of the Cadillac Tax may also prove beneficial if she makes it to the general election campaign, when she will be attempting to win over swing voters who are likely hostile to tax increases.