President Trump’s new budget calls for less spending on Medicare and food stamps and more on defense and on a wall on the southern border.

Democrats condemned the proposal, and the dispute raises the prospect of another government shutdown this year. That might seem to be a dicey proposition for the economy, but the administration doesn’t seem worried about a slowdown any time soon.

The president has described the current moment as “the greatest economy in the history of our country,” and the official forecast is rosy: around 3 percent growth in gross domestic product every year for the next decade, and even more in 2019 and 2020.

Yet some serious people remain nervous.

Job growth last month came in wildly below expectations. G.D.P. growth, which hit an annualized rate in excess of 4 percent in the second quarter of last year, has been fading ever since. The Federal Reserve Bank of Atlanta’s GDPNow forecast suggests that the current quarter’s annual growth rate might even be below 1 percent.