Right now it’s impossible to know. But among some things that are not improbable could be:
-Suppose he was able to cajole or shame (and he’s not bad at shaming) congress into limiting all budgetary increases (except possibly defense, depending) to the inflation rate. That would have a huge effect on the deficit over just a few years. “Zero based budgeting plus” he could call it.
-Suppose he required that Mexican beef be grown and treated with the same standards as American beef, and tested to ensure it. In one year, the beef imports from Mexico have nearly quadrupled and the American prices have crashed. But no change in the cost at the store. Perhaps better, suppose he got congress to withdraw from NAFTA entirely and again allowed “place of origin” labels, or at least insisted on it as a condition of remaining with NAFTA. Consumers can’t now decide to buy relatively clean American beef in preference to chemical-laden Mexican beef. That would make a real difference to ranchers and grain producers.
-Suppose he simply tied American compliance with China’s “most favored nation” status to full access to Chinese markets. So, for example, Caterpillar could sell heavy machinery made in Moline to China instead of the same machinery required by China to be made in China.
-Suppose he simply ordered the EPA to back away from its restrictions on coal. Miners could go back to work. Machine manufacturers could sell mining equipment again. In my state, it would save every household $1500/year by one estimate. Probably true in others.
-Suppose he got a tariff passed by which agricultural products legally shipped here from other countries had to bear the cost of fighting illegal agricultural products shipped here from the same country. Mexico might actually have to get serious about fighting the drug cartels for once. While Mexico was getting that done, we could buy our winter strawberries from Chile. Might cost a little more, like Chilean grapes, but we could live with that.
-And he could order EPA to reverse WOTUS, which puts the army in charge of every farm pond and dry wash in the country. Want to clean out your pond? Gotta call the army first now and get its permission.
-And what about making psych, alcohol and drug treatment optional in health insurance instead of mandatory? He could do that with a stroke of the pen. And how about dismissing the suit against the Little Sisters of the Poor and making free abortifacients no longer a feature of Obamacare. It would save Americans a lot of money.
-And what if he declared a moratorium on new government buildings and ordered the sale of thousands of government buildings that are no longer in use?
-And, wonder of wonders, what if some departments’ budgets were actually cut?
-And what if he ordered the sale of all government lands the Clinton administration gobbled up?
-And with a stroke of the pen he could restore irrigation to a great deal of California, and put a lot of unemployed people back to work.
-And instead of throwing ever more money at gold-plated colleges and universities, he tied student loan amounts to the colleges’ thrift in spending money on teaching instead of lavish buildings, fountains, statuary and the like. And wonder of wonders, colleges were financially rewarded for bringing tuition down to affordable levels. That’s not absurd. At one time, most state colleges’ tuition was zero or very little.
Some of those things would require working it out with congress. Some wouldn’t. But if an unlearned person like me can come up with some things, how many more could someone effect if he had some sharp-eyed “green eyeshade boys” go through the budget?