The mainstream media almost never mentions the Congressional Budget Office without adding the adjective “non-partisan.” But the CBO is staffed by folks who, in real life, are probably partisan. And given the pool from which its staff is drawn, most very likely are partisan Democrats.

Are its findings infected by partisan bias? I don’t know. But something funny is going on with the CBO’s assessment of the impact of repealing Obamacare’s individual mandate. Yuval Levin, who doesn’t allege a partisan conspiracy, has the details.

When Obamacare repeal was proposed, the CBO estimated that ending the individual mandate would result in a massive loss of coverage. Congressional Republicans disputed the scope of the coverage loss, arguing that the CBO was overstating the degree to which the mandate causes people to purchase health insurance.

Levin agrees with this critique. He finds the CBO’s coverage estimates “indefensible in light of the evidence of the past few years and the academic literature on the subject.”

Defensible or not, the CBO’s estimates played a major role in the debate over repealing and replacing Obamacare. It might have caused the loss of Republican support that doomed the “repeal and replace” effort.

Now, though, some Republicans seek to take advantage of the CBO’s coverage loss estimates. They propose repealing the Obamacare mandate as part of the tax reform legislation. And based on the CBO’s estimates, they claim that this repeal would produce a savings of several hundred billion dollars.

Because the CBO has very likely overestimated the coverage loss associated with repealing the mandate, the alleged several hundred billion dollars of savings might well be mostly mythical. However, Congress operates in the CBO’s imaginary universe, as Levin puts it. If CBO estimates are to used authoritatively in the Obamacare debate to pump up the lost coverage numbers, it’s fair to use them authoritatively in the tax reform debate to pump up the savings numbers. Indeed, it would be unfair not to.

Yet, now that Republicans are relying on the CBO estimates, the CBO wants to change hem. Hence, this announcement:

The agencies [the CBO and its companion Joint Committee on Taxation] are in the process of revising their methods to estimate the repeal of the individual mandate.

To be clear, the CBO is not dropping a substantially revised savings number into the tax reform debate. It states:

Because that work [the revised methodology] is not complete and significant changes to the individual mandate are now being considered as part of the budget reconciliation process, the agencies are publishing this update without incorporating major changes to their analytical methods.

Levin says the updated number is in line with the previous one.

But this doesn’t mean the CBO isn’t tilting the playing field. It has signaled that the savings number the Republicans are citing — which corresponds to the one the Democrats flogged during the Obamacare debate — isn’t reliable. Just as Republicans argued during the Obamacare debate.

Even without a significantly lower new number, that’s a bombshell.

As noted, Levin says he’s “not inclined to the most conspiratorial readings of the timing of this change.” But it seems to me that those readings must be entertained.