GOP presidential nominee Mitt Romney celebrated last week’s “victory” at the first debate in Denver — at which he promised to cut off Big Bird’s funding — by telling youth-targeting Nick News that he would not participate in Nickelodeon’s long-running “Kids Pick the President” special.

It’s only the second time a candidate has declined to participate.

Romney’s camp cited time constraints, the Viacom-owned cable network said Monday.

It takes about 30 minutes for a candidate to participate, which each does by answering a set of questions submitted to them by kids, the special’s exec producer, Linda Ellerbee, told the TV Column on Monday.

Nickelodeon has run this franchise for the past six presidential-election cycles; the seventh will be telecast Oct. 15. The special has come to loom large-ish because in some circles (gambling ones, for instance), it’s become a kind of bellwether poll. As soon as the special is telecast, Nickelodeon opens up online voting; this year, the voting results will be announced Oct. 22.

Four years ago, for instance, Nickelodeon declared Barack Obama the winner of its online ballot. A franchise-record 2.2 million votes were cast in what the cable network noted is not a scientific poll. Obama received 51 percent of the vote to Republican John McCain’s 49 percent.

Ellerbee, who is also the special’s host, put out a statement in 2008, saying: “It’s important to take note of who won the ‘Kids’ Vote,’ simply because so many kids vote the way their parents will.”

In five of the past six presidential elections, the kids have correctly predicted the winner (they got it wrong in ’04, picking Democratic Sen. John Kerry). That’s also the only other year that a candidate has declined to participate in the Q&A special, Ellerbee noted.

“We began communicating with the [Romney] campaign on April 30 and they were very encouraging, and now, six months later, it’s: ‘Sorry, we couldn’t find time, the governor is just too busy’ — and has been too busy for the past six months,” Ellerbee told the TV Column.

“By answering kids’ questions directly, candidates show respect for kids,” Ellerbee said in Nickelodeon’s news release about the special, as though she meant it to sting.

President Barack Obama sits down with Nick News. (Lucky Duck Productions )

Obama didn’t just agree to participate; he invited the crew members to the White House, where they taped his responses to the kids’ questions Sept. 19.

“It’s no surprise Romney decided to play hookey,” Obama’s camp said Monday in a statement about his opponent’s decision.

“Kids demand details, and I’m sure they want some answers on why Romney could increase their class sizes, eliminate their teacher’s jobs, raise taxes on their families and slash funding for Big Bird. Unfortunately for Mitt Romney, ‘The dog ate my homework’ just doesn’t cut it when you’re running for president.”

The White House also said Monday in a statement: “It’s a long-standing tradition for presidential candidates to appear on Nickelodeon’s ‘Kids Pick the President’ program, and it’s a good opportunity for President Obama to speak directly to American families about his plan to keep the country moving forward, get folks back to work and strengthen the middle class.”

Former president George W. Bush “was all over doing this in 2000,” Ellerbee noted. “In 2004, John Kerry turned us down, and we informed the Bush campaign – as we informed the Obama campaign about Romney — and Bush said, ‘If Kerry is not doing it, I’m not gonna do it.’ That’s the only time someone has turned us down.”

A Nick source says the network was told late last week that Romney “would not be available to participate.”

Nick has already aired the first of this cycle’s election specials, in which kids voted online as to what were their top eight issues of this campaign cycle. At that special, telecast last month, Nickelodeon revealed that the viewers thought the top issues facing the country were:

1. Same-sex marriage

2. Education

3. Health care

4. Taxes

5. Immigration

6. Iran

7. Energy

8. Jobs.

Nickelodeon programs its viewing for kids 6 to 14 years olds, though there is no way on the channel’s Web site to prevent those older, or younger, from voting.