TRUMP’S FISCAL STIMULUS PUTS DEMOCRATIC ECONOMISTS WHO PROMOTED IT UNDER OBAMA IN A BIND.

administration makes bad infrastructure decisions and wastes a lot of money, measured GDP still is going to rise. Don’t be fooled.

There is another reason why short-run GDP is a misleading guide to stimulus: The money spent eventually has to be paid back. So today’s GDP boost will be offset by a contraction in five, 10 or 20 years.

In Keynesian theory, fiscal policy only works well if you use it in down times and pay off the bill during a boom. Trump seems ready to do the opposite by upping spending as the economy approaches Furthermore, some parts of the stimulus truly were beneficial, for instance the aid to state and local governments that limited the need for temporary layoffs. But a serious evaluation of the Obama stimulus, and its longer-term consequences, remains to be done.

Many Democratic economists are in a bind when it comes to criticizing the forthcoming Trump stimulus, as they’ve spent the last seven years neutering their best arguments. The awkwardness is evident in writers such as Paul Krugman, who has argued for a massive stimulus for many years, including for 2016, claiming it would come close to paying for itself, even if much of the money were to be wasted. Now Krugman sees his arch-enemy Trump recommending more government spending, and he can’t bring himself to simply endorse someone else’s version of that idea.

Republican legislators also face a dilemma. Many of them, including Paul Ryan, went along with the big government spending increases of the Bush administration, when Republicans controlled the executive and legislature. The conservative wing of the party made them swear to never do it again, but will they stick to that promise? I predict Trump will offer a big enough tax cut to get most of them on the spending bandwagon once again.

The real danger is that a year or two from now, Trump will be a popular president, pointing to real gains in GDP numbers, even if his policies aren’t better for the longer run.

The best scenarios for a Trump presidency involve a lot of checks and balances, backed by public skepticism, not more popularity and populism. It’s up to economists to help enforce such critical thinking, but the fiscal-policy rhetoric of pro-stimulus economists has been pushing discourse in the wrong direction. That’s one bill to come due sooner than many of us had been expecting.