White House Office of Management Director Mick Mulvaney on Wednesday opened fire on the Congressional Budget Office, asserting in an interview with the Washington Examiner that the day of the institution as an authoritative non-partisan arbiter of legislation "has probably come and gone."

Mulvaney, speaking in his office in the Old Executive Office Building, described the CBO's scoring of the House Republican healthcare bill as "absurd," arguing that it was a perfect example of why Congress should stop being so deferential to the group.

"At some point, you've got to ask yourself, has the day of the CBO come and gone?" Mulvaney said. "How much power do we give to the CBO under the 1974 Budget Act? We're hearing now that the person in charge of the Affordable Health Care Act methodology is an alum of the Hillarycare program in the 1990s who was brought in by Democrats to score the ACA."

He continued, "We always talk about it as the nonpartisan Congressional Budget Office. Given the authority that that has, is it really feasible to think of that as a nonpartisan organization?"

Mulvaney was referring to Holly Harvey, who has been the head of the CBO's health analysis division since 2009 and had served during the Clinton administration as a senior analyst in the office of the assistant secretary for planning and evaluation at the Department of Health and Human Services.

Mulvaney was particularly critical of the CBO's recent estimate that the House-passed healthcare bill would result in 23 million fewer people with health insurance. He argued that the CBO's model assumed that the mandate requiring individuals obtain coverage has a lot more influence on people's decisions than it does in real life.

"Did you see the methodology on that 23 million people getting kicked off their health insurance?" he said. "You recognize of course that they assume that people voluntarily get off of Medicaid? That's just not defensible. It's almost as if they went into it and said, ‘Okay, we need this score to look bad. How do we do it?'"

He added the CBO assumptions were "just absurd. To think that you would give up a free Medicaid program and choose instead to be uninsured is counterintuitive."

He suggested that there was a bias at work. "If the same person is doing the score of undoing Obamacare who did the scoring of Obamacare in the first place, my guess is that there is probably some sort of bias in favor of a government mandate," he said.

Without the CBO, he argued that multiple entities could do their own scoring, using the hypothetical example of a proposed regulation to eliminate a type of light bulb.

"I would do my own studies here at OMB as to what the cost and benefits of that reg would be," he said. "And other folks would do their studies from the outside. And those would come with their natural biases. The Heritage Foundation comes in and says it's going to cost a lot. Brookings comes in or the Center for American Progress says the benefits would be great. You and I and other lawmakers can sit down and say, ‘Okay, we think that this is where it is, and we'll make our decisions based upon that.'"

He said, "The days of relying on some nonpartisan Congressional Budget Office to do that work for us has probably come and gone."

Asked what would happen in a scenario in which, say, a Democratic administration says a bill costs $500 billion and Heritage Foundation puts out a report saying the same bill would cost trillions, Mulvaney responded, "Then they would do it and if it works, they would get re-elected and if it doesn't, they don't. And that was the way it worked before the Congressional Budget Office."

Mulvaney said he'd have no problem with the CBO continuing to exist if it merely wanted to "opine" or if its analysts tried to "recapture their true nonpartisan nature." But absent that, he said the institution shouldn't be deferred to on matters such as what meets the requirements for budget reconciliation or "pay as you go" budgeting.

"To defer to them, I think is giving them way too much authority," he said. "Certainly there is value in having that information, especially if they could return to their nonpartisan roots. But at the same time you can function, you can have a government, without a Congressional Budget Office."