President Obama didn’t repeat the mistake of his lackluster debate performance in his first post-debate appearance on Thursday, coming out swinging at Mitt Romney.

“We had our first debate last night,” Obama said at an outdoor event at Sloan’s Lake Park in Denver on Thursday. “When I got onto the stage I met this very spirited fellow who claimed to be Mitt Romney. But it couldn’t have been Mitt Romney, because the real Mitt Romney has been running around the country all year promising $5 trillion in tax cuts for the wealthy. The fellow onstage last night said he didn’t know anything about that.”

Obama seemed to be knocked off message in the early stages of Wednesday’s debate, as taxes, and an aggressive Romney, dominated the opening segments.

Romney defended his tax plan after facing repeated claims from Obama that it would hurt the middle class and explode the deficit. The former Massachusetts governor said his plan to cut tax rates across-the-board would be paid for by ending tax preferences for the highest earners, and said that under no circumstances would he increase the tax burden on the middle class.

One of the few moments of levity came when Romney said part of his plan to reduce federal spending would be to cut funding to public television.

“I like PBS; I love Big Bird. Actually I like you, too,” Romney said to debate moderator Jim Lehrer, the host of PBS's "NewsHour." “But I'm not going to keep on spending money on things to borrow money from China to pay for."

Obama had a ready-made quip to play off the remark, and used it to hammer Romney over his tax plan.

“When asked what he would do to reduce the deficit, he said he would cut funding to public television,” Obama said Thursday. “That was his answer. Thanks goodness somebody is finally getting tough on Big Bird. It’s about time. We didn’t know that Big Bird was driving the federal deficit. His math doesn’t add up, and I had to spend a lot of time last night trying to pin him down.”

Obama also hit Romney over other instances from the debate in which he said the GOP challenger had flip-flopped.

“The real Mitt Romney said we didn’t need more teachers in our classrooms,” Obama continued. “But the fellow onstage last night, he loves teachers, can’t get enough of them. The Mitt Romney we all know invested in companies that were pioneers in outsourcing. But the guy onstage last night said he doesn’t even know about laws that encourage offshoring.

“He said that if it’s true he must need a new accountant. Now, we know for sure it was not the real Mitt Romney because he seems to be doing just fine with his current accountant. So you see, the man onstage last night — he doesn’t want to be held accountable for the real Mitt Romney and what he’s been saying for the last year, and that’s because he knows full well we don’t want what the real Mitt Romney has been selling for the last year.”

Romney spokesman Ryan Williams shot back in an email to The Hill, saying the president was in "full damage-control mode" from the debate.

“In full damage-control mode, President Obama today offered no defense of his record and no vision for the future," Williams said. "Rather than a plan to fix our economy, President Obama simply offered more false attacks and renewed his call for job-killing tax hikes. Last night, Mitt Romney demonstrated why he should be President, laying out the clear choice in this election. We can’t afford four more years of the last four years. We need a real recovery – and Mitt Romney has a real plan to deliver it.”