Republican 2012 presidential hopeful and former Utah Gov. Jon Huntsman talks with residents in Nashua, N.H. (Cheryl Senter/AP)

Jon M. Huntsman Jr. is making good on his pledge to be more aggressive with his opponents, saying he “wouldn’t necessarily trust” any of his opponents when it comes to handling the economy.

The GOP presidential candidate, in an interview with ABC’s Jake Tapper that aired Sunday, had harsh words for President Obama as well, saying that he didn’t lead in the fight over the debt ceiling.

“I have to say that there was zero leadership on display in terms of my opponents . . . zero leadership on display in terms of the president, who should have used the bully pulpit well ahead of time,” Huntsman said on “This Week With Christiane Amanpour.” “He should have walked away from the teleprompter. The people want you to speak from your heart and soul. Tell us where you want us to go. Tell us what you expect from Congress. Tell us what’s on your mind. That never happened.”

“And it waited until the eleventh hour, and then we had some of my Republican opponents who basically, I think, recommended something that would have been catastrophic for this economy,” he said.

Huntsman, who launched his campaign vowing to be civil, has struggled to gain traction in early polls, and with his moderate views and former job as Obama’s ambassador in Beijing, has yet to find a constituency.

In the past week, with the entry of Texas Gov. Rick Perry in the race, Huntsman’s candidacy has become something of an afterthought, yet he gained some buzz this week over Twitter by taking Perry to task for doubting the science of evolution and global warming.

On Twitter, Huntsman said: “To be clear, I believe in evolution and trust scientists on global warming. Call me crazy.”

The comments went viral, boosted Huntsman’s Twitter footprint and revealed a more combative, if humorous, side of the former Utah governor.

His campaign debut was marked by fanfare and much media coverage — his family is featured in a Vogue magazine spread in the September issue — yet as a candidate he has yet to find his footing, and his campaign has been marred by several departures and some infighting.

While he still only rarely calls his opponents by name, he is aiming to stake out a more middle-of-the-road path in a party that tilts right. His road to victory relies heavily on New Hampshire, where he has spent the bulk of his time and resources.

His criticism of Perry seemed squarely aimed at New Hampshire, given that the primary there will include independents, Democrats and more-moderate Republicans.

He suggested that Perry’s comments were outside the mainstream.

“I think there’s a serious problem. The minute that the Republican Party becomes . . . the anti-science party, we have a huge problem,” Huntsman said about Perry’s comments on global warming. “We lose a whole lot of people who would otherwise allow us to win the election in 2012.”

Asked if he thought Perry sounded “unpresidential” when he suggested that Federal Reserve Chairman Ben S. Bernanke would be treated “pretty ugly down in Texas” if he printed more money, Huntsman said, “Well, I don’t know if that’s pre-secession Texas or post-secession Texas,” referring to Perry’s 2009 comment suggesting that Texas could leave the union. “But in any event, I’m not sure that the average voter out there is going to hear that ‘treasonous’ remark and say that sounds like a presidential candidate, that sounds like someone who is serious on the issues.”

In the most recent polls, Huntsman is still in the low single digits. By pummeling Perry, he is trying to make the case that he belongs in the top tier along with the Texas governor, former Massachusetts governor Mitt Romney and Rep. Michele Bachmann (R-Minn.).

“Every time we have these sideshows take place — finger-pointing and name-calling — it takes us that much farther off the ball, which is fixing our core in this country, is getting our economy fixed and creating jobs,” Huntsman said.