President Trump speaks in Washington, D.C., on April 27, 2017 Photo credit: AP Photo/Andrew Harnik.

What is the most important number in the Trump presidency?

Is it 52, the number of Republican senators, who are needed to advance his legislative agenda? Or maybe 140, the character limit on Twitter?

One of the critical figures was released Friday morning by the Commerce Department: the rate of economic growth. The economy grew at a sluggish 0.7 percent in the first three months of the year, the first such report under the Trump administration. That’s the weakest growth rate in about three years.

Taken by itself, that single figure showing a slow rate of growth in one quarter means little. But a lot of the Trump agenda is staked on robust economic growth in future quarters.

Remember that one of the main critiques of the Obama years is the anemic rate of growth coming out of the recession he inherited in 2009. Trump pounded Obama in the fall for being “the first president in modern history not to have a single year of 3 percent growth”—a statement that even PolitiFact rated as “mostly true.” The White House has set a goal of achieving 4 percent annual economic growth.

If the economy can grow faster, that means more people working, factories humming, and, critically for Washington, a whole lot more tax revenue. Ask Bill Clinton, who presided over 4 percent annual growth for four years in the late 1990s, how that kind of an economic boom can boost your legacy.

Faster growth, and the money that comes from it, can paper over a lot of problems. It can shrink the deficit, enable more spending, allow for easier tax cuts, and postpone the day of reckoning on entitlements. Many economists, though, doubt that Trump’s 4 percent goal is possible because they say there aren’t enough U.S. workers, and the prospect of more immigrants is, let’s face it, dim.

“The reality is that 4 percent is probably beyond our reach, because we would need more labor force growth,” says Mark Vitner, senior economist with Wells Fargo, in an interview with THE WEEKLY STANDARD. “Trump is not an economist, but he’s making the point that we should be doing better than we are right now.” Vitner says lower tax rates and greater incentives for business investments would help.

The slow first quarter growth figure could underscore the urgency of tax reform to get the economy moving. Trump unveiled an ambitious pro-growth tax plan this week that conservatives applauded but that liberals are sure to #resist.

Here’s another key number: 14. That’s the number of quarters remaining until the next presidential election. The economic growth numbers in those quarters will render an important verdict on the Trump presidency—and whether it will continue into a second term.