Editor's note: Alexander Heffner, an undergraduate at Harvard concentrating in history, is director of ScoopSeminar.org, an education and journalism nonprofit
(CNN) -- "If we can, we'll be able to complete an agreement that supports jobs and prosperity in America," President Obama recently wrote about his trip to Asia.
And just before the midterm election, he conceded to Jon Stewart of "The Daily Show" that "Yes we can ... but it's not going to happen overnight."
If nothing else, these words testify to the president's change of tenor -- from "Yes, we can" to "If we can" -- and young people didn't elect Obama to be an "If we can" president. They said as much by not returning to the ballot box last Tuesday.
Young people and black Americans who had been so moved by Obama's presidency voted in slim numbers this time. Exit polls showed that voters ages 18 to 29 made up 11 percent of the electorate -- a sharp drop from the 18 percent in 2008 and the lowest percentage in two decades -- and only 10 percent of African-Americans voted.
Obama seemed resigned to defeat, even embarrassed, after the onslaught of GOP congressional victories. But to be a generation-defining leader, Obama must never relinquish his vision in the face of this.
In vigorous pursuit of his Great Depression-fighting agenda, FDR did not yield to Republican leadership or wavering Democrats, and LBJ did not prioritize political unity over passage of the 1964 Civil Rights Act. Because of Ronald Reagan's leadership -- which many Democrats protested -- Communist dominoes fell.
During a campaign editorial board meeting with the Reno Gazette-Journal in 2008, candidate Obama alluded to this: "I do think ... 1980 was different. I think Ronald Reagan changed the trajectory of America in a way that Richard Nixon did not and in a way that Bill Clinton did not," he said.
"I think he [Reagan] just tapped into what people were already feeling, which was we want clarity, we want optimism, we want a return to that sense of dynamism and entrepreneurship that had been missing."
But the president has been unwilling to practice this energetic leadership from the bully pulpit, especially now that it will mean challenging, tooth-and-nail, a Republican House majority.
Obama's admission that he needs to do a better job, and the facial expressions pictured in newspapers across the country that make him look depressed, will not lead to confidence in his ability to do that "better job."
It's one thing for the president to be tired or on a brief hiatus from the political offensive. It's another to lose the audacity that guided his core principles.
"What the **** has Obama done so far?" is an inventive website that tried to get listless young voters to the polls last Tuesday by naming some of the president's achievements over the last two years, including his education innovations, support for scientific research, health care and financial reform, and increased consumer protections.
But continued action on such things as fiscal reform and deficit reduction are not possible with an executive who is so willing to curtail his own influence.
President Obama needs to recharge his engine and govern with the same confidence he showed in the campaign two years ago. If he doesn't, the parties will continue to skirmish without progress, and young voters from the 2008 campaign (and prospective new ones) will not re-elect him.
The opinions expressed in this commentary are solely those of Alexander Heffner.