Barack Obama hasn’t been in a high-stakes, nationally televised presidential debate in nearly four years. Mitt Romney was in plenty of them over the past 18 months. Last night, it showed.

Heading into yesterday’s encounter at the University of Denver, polls showed that voters by a wide margin were expecting Obama to win the three debates that he and Romney have agreed to. But not only did the president fail to knock out his challenger last night, there were long stretches when it wasn’t even clear he had remembered to lace up his gloves. On issue after issue, in exchange after exchange, Romney was focused, clear, interesting, and engaged, while Obama repeatedly came across as distracted, irritated, and vague. The former Massachusetts governor was plainly enjoying himself. The president seemed to want nothing more than to run out the clock and bring a painful evening to an end.

I didn’t hear any devastating zingers, but Romney came equipped with memorable lines. The Obama economic philosophy, he said early on, amounts to “trickle-down government.” The tens of billions of dollars the administration has sunk into failed “green” energy companies, he quipped, shows that “you don’t pick winners and losers, you just pick the losers.” To the president’s repeated claim that Romney’s tax proposals would inevitably result in higher taxes on middle-class earners, the GOP nominee replied affably that as a father of five sons, he was used to people saying something untrue over and over in the hope that repetition would make it more convincing.

When asked for examples of federal spending he would like to cut, he cheerfully cited subsidies for PBS. “Sorry, Jim,” he smilingly told moderator Jim Lehrer, who is practically a PBS icon. “I like PBS. I like Big Bird – I even like you!” A humorless Obama, by contrast, snapped at Lehrer when he thought the moderator had cheated him out of five seconds of response time.

Romney channeled Muhammad Ali last night, floating like a butterfly, stinging like a bee. He left Obama on the ropes.

(Jeff Jacoby is a columnist for The Boston Globe. His website is www.JeffJacoby.com).