“What the hell’s the presidency for?”

That was President Obama speaking on Thursday, quoting former president Lyndon B. Johnson. Obama was in Austin at the three-day conclave marking the 50th anniversary of the Civil Rights Act of 1964.

Seeking to capture the essence of Johnson and his presidency, Obama revealed something about his own.

Johnson was a larger-than-life figure when he was president. In memory, he has sometimes become an even larger presence, one that has been a source of both inspiration and exasperation to those around Obama. The question they hear so often is: Why can’t this president be more like LBJ?

Commentators on cable television talk about it all the time. They say Johnson possessed legendary powers of persuasion and a mastery of the legislative process, and they contrast LBJ’s successes in Congress with those of a president whose legislative agenda has repeatedly stalled and whose relationships on Capitol Hill are notably lacking.

During the 2012 campaign, Obama’s advisers heard the same thing in focus groups with sympathetic voters. These voters had no truck with the Republican tactics of obstruction, but they wondered why Obama lacked whatever LBJ had. Why couldn’t Obama make the machinery work better? Why couldn’t he cajole and threaten and sweet talk and bully the Congress into action the way Johnson had?