He’s back.

After a disappointing and lackluster performance in the first debate, President Barack Obama came to the second debate in Long Island with a force and tenacity that demonstrated why he is the superior candidate.

The most notable aspect of the 90-minute debate at Hofstra University was the president’s persistence in not allowing Mitt Romney to offer misrepresentations and half-truths to go unchecked. Time and time again, Obama pointed out Romney’s shifts on a host of topics.

“Governor, what you’re saying is just not true,” Obama said, repeatedly, taking the former Massachusetts governor to task on everything from energy and tax policy to foreign affairs. Indeed, Obama refused to let Romney get away with his endless streams of fiction and unsustainable theories.

Even on the topic of the role of coal in the nation’s energy strategy, Obama made clear he would let nothing slide. Romney presented himself as the champion of coal usage, criticizing Obama as being uncommitted to the coal-producing industry. In turn, Obama took Romney to task, pointing out that the former governor had once condemned coal production as being unhealthy.

The president was at the top of his game when he challenged Romney about the governor’s vague and ill-defined tax plans. He pointed out that Romney, as a businessman and investor, would never accept such a “sketchy” plan from anyone. “And you shouldn’t either,” the president said, addressing the nationwide audience.

For more than a year, Romney has altered his positions on every major public policy issue, from immigration and abortion to energy and taxes. It was reassuring to see the president take him to task for shifting his views to a degree that makes the positions of Romney’s candidacy difficult to follow, let alone to find believable.

At one point, Obama pointed out that the architect of Arizona’s harsh and extreme immigration law had advised Romney on immigration. At the next turn, Romney continued to promote his punishing position of having undocumented immigrants self-deport. Obama talked about how his health care reform will add security to the lives of millions of Americans, and he noted that Romney had vowed to dismantle Obamacare, even though the former governor championed a similar health care package in Massachusetts. “That is not the kind of leadership you need,” Obama said.

The president’s vigorous debate performance came not a minute too soon. After the previous meeting with Romney in Colorado, many of Obama’s strongest supporters were left dispirited. In that debate, Obama carried himself as though he had been asked to make casual remarks to a college political science class rather than to present an assertive vision of his stewardship in the Oval Office before a nationwide audience of 70 million people.

The most positive aspect of this second debate is that Obama presented himself as a leader with commonsense remedies to the challenges that confront the nation. Even more than that, it would be hard not to view Obama as anything but a man with a steady and forceful command not only of the debate itself, but also of the nation he leads. It was a comforting scene.