Mick Mulvaney, the Republican congressman and fiscal hawk nominated by Donald Trump to head the White House Office of Management and Budget, will, if confirmed, be in charge of creating and promoting Trump’s federal budgets, a position that would put him at the center of debates within the administration and with Congress over the president’s priorities. As the OMB director, Mulvaney would also have power to advance or impede federal regulation, because many proposed rules have to pass muster at OMB before they are issued.

The traits Mulvaney brings to the job include a pronounced hostility to both federal spending and federal regulation — the basics of functional government. He rode the anti-deficit, anti-regulation Tea Party wave into Congress in 2010 and is a founder of the far-right House Freedom Caucus.

In recent years, he has advocated shutting down the government rather than passing legislation to keep the nation and the economy running, and he was one of several dozen House Republicans who refused to back a deal to avoid default on the national debt by raising the statutory debt limit. In 2013, he nearly torpedoed a $50.7 billion relief bill in the wake of Hurricane Sandy by pressing for draconian spending cuts to offset the emergency funds. He has voted many times to repeal the Affordable Care Act, calling it a “government takeover” of health care.

Because all policies affect the budget, all policies, directly or indirectly, fall into the OMB’s purview at some point. Mulvaney would thus play an important role in decisions about how to dismantle the ACA, a Republican priority. He would also have a voice in discussions over Trump’s infrastructure plan. As a sworn enemy of government spending, it seems likely he would prefer to finance the plan by giving tax cuts to private developers rather than sending federal money to the states — a move that would create windfall profits for a few private businesses without adequately meeting public infrastructure needs.

On regulatory actions over which the OMB has a say, there is every reason to believe that Mulvaney, serving in a Trump administration, would water down or indefinitely delay proposed rules. During his time in Congress, he has supported regulatory rollback efforts, including legislation to strip President Obama of executive rule-making authority. The rules over which the OMB has influence include energy and environmental standards, labor protections and food safety.

An unanswered question is how a deficit foe like Mulvaney could actually get behind the Trump economic agenda. Trump has proposed tax cuts that would cost $6.2 trillion over 10 years, according to estimates by the nonpartisan Tax Policy Center. On top of those cuts, he has proposed vast new spending on defense and infrastructure. The combination of tax cuts and new spending would result in a huge increase in federal debt — which Trump and Mulvaney could cite as an excuse to make devastating spending cuts to other federal programs and services.

Or Mulvaney could sign off on reckless budgets by pushing for rosy economic assumptions that can make it seem as if revenue will rise and deep deficits will disappear.

At this juncture, it is impossible to know how Mulvaney will get Trump’s numbers to add up. But it is safe to assume that if he does pull off that trick, the results won’t bode well for effective government.