Why has Barack Obama—one of the most eloquent and thoughtful of recent presidents—become such a terrible politician? Midway through his sixth year in office, his ineptitude is pretty clear. He frustrated and demobilized the huge base he built during his campaigns and, unless the polls turn around quickly, will be watching from the White House as the GOP takes full control of Congress this fall. On Tuesday, the Times offered some new evidence in an article about his frosty relationship with Senate Democrats.

Obama is governing a nation full of discouraged, sometimes angry people, and he seems unable or unwilling to address their discontent in any sustained or effective way. Worse, except for those deluded souls who believe he’s a tyrannical socialist, the president has become a rather boring and insignificant figure. His response this Monday to the outrage in Ferguson, Missouri—"Let us build, not tear down. Listen, not just shout”—neither persuaded nor mollified. Keeping calm is not a political strategy.

The familiar diagnoses of his failure are not particularly convincing. Yes, Obama shuns rigid ideologies and hankers for bipartisanship, but then so do most voters. His racial identity does force him to be rhetorically cautious, lest he seem to care more about black people than other Americans. But it also helped him win the 2008 Democratic primary, and then boosted minority and young voter turnout to give him an easy victory in the general election. And if Obama is indeed as arrogant some say he is, then so were some of the more consequential chief executives who preceded him—Andrew Jackson, Woodrow Wilson, Lyndon Johnson, and Ronald Reagan.

Each of those four presidents—as well as greater ones like Lincoln and FDR—built loyal followings and retained them for nearly their entire time in office. A major reason for their political success was that both admirers and detractors knew exactly what they stood for because they took every opportunity to explain it, whether it was Jackson’s abhorrence of financial monopoly, Lincoln’s vow to stop the spread of slavery (and then to abolish it entirely), FDR’s desire to uplift “the forgotten man,” or Reagan’s loathing for “big government.” These presidents’ critics made little headway by distorting their objectives. Most Americans refused to believe that FDR was a tyrannical leftist or Reagan a heartless bigot because they had often seen and heard each man speak, with passion and empathy, about the matters closest to his heart.

But if Obama cares deeply about anything he has accomplished or intends to accomplish, he has made no serious or sustained attempt to let us know. Instead, he typically delivers a big speech or two about a subject—whether the ACA, economic inequality, or immigration reform—and then essentially stops talking about it, even when, as with the income gap, he has public opinion on his side. No topic seems to hold his interest very long, and so he bounces around without ever persuading the American public...