Many Washington politicians aren’t very good with numbers. Somehow we expect more of the budget director — unless it’s Mick Mulvaney.


The Trump administration’s director of the Office of Management and Budget was at it again this weekend, suggesting the budget outline just approved by the Senate isn’t a deficit-buster and that congressional rules discriminate against spending reductions. He also falsely criticized a bipartisan effort in the Senate for a temporary health fix as a giveaway to insurance companies.


This is the same Mr. Mulvaney who in his first budget earlier this year made a $2 trillion miscalculation by double counting. He trashed the Congressional Budget Office when it differed from his dubious numbers. And he has forgotten his crusade, as a South Carolina tea party Republican, against federal deficits — even opposing increasing the debt ceiling.


On “Face the Nation,” he looked like a born-again fiscal dove by embracing the Senate budget plan that seeks to pave the way for a big tax cut. He suggested this will produce a gusher of revenue leading to a balanced budget.


He’s wrong on that, too. Outside analysts, like the Committee for a Responsible Federal Budget and the Tax Policy Center, estimate that budget would add somewhere between $1.5 trillion and more than $2 trillion to the deficit over the next decade. The administration could alter its tax cut plans to increase or decrease that number but no one believes the deficit will shrink under any scenario.


Mulvaney insisted the administration is still pushing big spending cuts but said it was hamstrung not only by a lack of political will in Congress but also by longstanding rules. The 1974 Budget Act, he contended, “says if you spend $100 last year and $104 this year, we call it a cut.


“I’m not making that up,” he said.


Yes, you are, Mr. Director. That measures cites the constant buying power of appropriations plus inflation. If spending goes up by 4 percent and inflation rises 5 percent, that is a cut in real terms. You could test this by volunteering to take a 1 percent increase in salary next year. What will that feel like after inflation, which has been hovering at around 2 percent, takes its cut?


In the television interview, he also charged a compromise health care bill offered by Sens. Lamar Alexander, R-Tenn., and Patty Murray, D-Wash., was a gift to insurance interests.


Trump’s opposition, after first supporting it, he said, can be summarized thusly: “I don’t want to give this money to insurance companies. I don’t want to gives this money to these CEOs who make tens of milli0ns of dollars.”


As refreshing as it is to see this right winger’s insistence that instead money go to “folks who are being hurt,” he got his facts jumbled again. The bipartisan bill would fund Obamacare’s insurance subsidies, which President Trump decided to suspend, destabilizing the entire market by threatening loss of coverage for some and premium hikes for others.


But the Affordable Care Act requires insurance companies to offer low-income Americans lower deductibles and co-payments. The companies are reimbursed for most of that cost but do not make a profit on this.


Stan Collender, a longtime Washington budget policy wonk, just shakes his head at Mulvaney’s aversion to facts: “He is a disaster.”


Albert Hunt is a Bloomberg View columnist. He was the executive editor of Bloomberg News, before which he was a reporter, bureau chief and executive Washington editor at the Wall Street Journal.